While mere use of the word or logo without registration is enough to create common law trademark ownership rights, those rights only extend to the geographical area where the mark is being used. A Federal Trademark registration is much stronger protection because it provides national protection.
There is no magic number of times that it must be used
I suggest you register immediately.
As a general matter, the rule is that there must be "bona fide" use in interstate commerce. There is no hard and fast rule that I am aware of to quantify that, likely because it could vary with the goods/services involved. What I would say is that, if you have 1 sale across state lines that is likely a "fluke", I would not consider that sufficient, but if you are trying to sell in interstate commerce and have at least a few sales (2-3 even) and legitimately expect to make more such salesin the future, whether it is monthly, weekly or yearly should not matter and need not be quantified.
You could file an Intent to Use (ITU) application now if you have a bona fide intent to sell in interstate commerce, which will stake a claim to the mark and allow you to prove use later in order to get it.
Talk to a trademark attorney who will be able to guide you based upon your particular facts.
Good luck, I wish you unparalleled success!
This information is intended to be general and educational in nature. It is not intended to be specific legal advice or establish an attorney-client relationship. I require a signed retainer agreement from a potential client to establish an attorney-client relationship and before I will provide specific legal representation.
The use in interstate commerce is a requirement for federal trademark registration.
For goods, "interstate commerce" generally involves sending the goods across state lines with the mark displayed on the goods or the packaging for the goods.
The term "use in commerce" means the bona fide use of a mark in the ordinary course of trade, and not made merely to reserve a right in a mark. You cannot create a strawman sale just to satisfy the requirement.
You can begin the process of obtaining a federal trademark, and later file proof of its use in interstate commerce, interstate commerce is not a condition precedent to filing for a federal trademark, but it is a requirement that you must satisfy to complete the registration. If you start the filing process and later change your mind you could abandon the application.
You should consult with a competent trademark attorney in your jurisdiction to determine your strategy.
My colleagues offered very good insights. I would only add that the modern approach would be that you need only have the good offered for sale and a picture of the good ready for shipment, for example, with the mark clearly visable would be an adequate specimen to show "use." The USPTO does not require that you show a proof of sale.
As noted you also have the option of filing an intent to use. Once the mark is registered there are no rules about how often it must be used. Unless it goes abandoned (loosely meaning you have not used it as described for at least two years) you really would have no worries. There are renewal periods that need to be complied with as well.
I would suggest you discuss this over with a lawyer in more detail and be sure to have a proper clearance search conducted (see link below) before you make any investment in it. I will link you to some general helpful info below and most of us here, including myself, offer a free phone consult.
The law firm of Natoli-Lapin, LLC (Home of Lantern Legal Services) offers our flat-rate legal services in the areas of business law and intellectual property to entrepreneurs, small-to-medium size businesses, independent inventors and artists across the nation and abroad. Feel free to call for a free phone consultation; your inquiries are always welcome: CONTACT: 866-871-8655 Support@LanternLegal.com DISCLAIMER: this is not intended to be specific legal advice and should not be relied upon as such. No attorney-client relationship is formed on the basis of this posting.
You need to know a lot more about trademarks and copyrights than the specific question you asked. I can tell by your question and comments in response to the sound advice of my colleagues that you have misguided understandings of many of the basics concerning intellectual property law, and that you are going to get yourself into big trouble if you do not retain legal counsel to assist you. You also need to educate yourself on the basics of intellectual property law as they relate to the fashion business. Failure to lay the proper legal foundation for your clothing line could be disastrous. For example, before choosing a trademark to brand your clothing line, it is critical that your obtain a trademark clearance analysis from counsel---if you choose a brand name that violates someone else's trademark your investment in branding may be lost.
Further, trademark rights arise from use in commerce, not registration. Registration is always a good idea, and you can register on an intent to use basis, but you have to be able to demonstrate actual bona fide use in commerce within six months. Bona fide use is more than offering to sell a few items across state lines. Use requires consistency and regularity over a reasonable period of time---a one shot offer to sell a sample from your clothing line will not suffice. When you file an "intent to use" application for a clothing line, you need to be reasonably confident that within six months you will have commenced offering to sell the clothing line across state lines as part of a promotional campaign consistent with how companies in the clothing business typically operate. If you will not have sufficient inventory to begin this promotional campaign within six months, then you may not be ready to file an intent to use application. Quite obviously you need to retain intellectual property counsel to guide you through this and many other issues. If you do not have a budget for intellectual property counsel then, quite frankly, you are not ready to develop a clothing line and operate this business.