As an initial matter, a paralegal cannot give legal advice. A paralegal does not necessarily have any legal training whatsoever. Only a licensed attorney can give legal advice. I encourage you to speak with an experienced immigration attorney about the matter prior to filing any documents on behalf of your mother.
Your mother will likely have an immigrant intent problem. It does not really matter how long you wait if the intent to immigrate was present. I would recommend that she not seek adjustment of status in the United States if her intent when she entered was to immigrate. You could file the immigrant visa petition now, but she could seek overseas processing of her immigrant visa.
The process takes about 5 to 6 months in the United States assuming the case is properly filed and documented. The process for consular processing is approximately 8 months to a year. Assuming you filed for adjustment of status, she could also request advanced parole. This would allow her to travel. However, advance parole does not guarantee admission and therefore, travel should be limited. If she has an immigrant visa pending, it is highly unlikely she would be allowed to enter the United States in the future as a visitor. CBP would believe she has no intention of returning in compliance with her visa.
As for charges, you need to speak to an attorney directly. Attorney rates vary.
I agree. Intent issues are tricky. Do not take advice from a paralegal.
Take a look at this blog post that I've written on intent issues: http://www.swagatusa.com/archives/1081
Dhenu Savla, Esq.
This answer does not create an attorney-client relationship and is not meant to be relied upon as legal advice.
Do not take legal advice from a paralegal or a "notario", over the years I have see too many cases completely screwed up. Intent may certainly be a problem. I strongly suggest a personal consultation with an experienced attorney of your choice.
This is not legal advice and a client attorney relationship is not created. For a free consultation call (718)234-5588.
I agree with my colleagues. If I were you I would consult with an immigration lawyer to discuss how it happened that your mother came in on a visitor visa and now wants to adjust status. The specific facts are critical in determining whether it is safe to seek adjustment now. Do not make a decision based on advice of a paralegal.