You need to change the hearing to a contested hearing. A mitigation hearing is one that you have already ADMITTED THE CHARGE. Change it now.
See if there is any way to get the speeding ticket dismissed. Officers mess up all the time on tickets and the devise that was used to check the speed may be out of wack. Get an attorney and try to save your license.
You will have to check with DOL to see when the 6 months started. The would be able to get you that info over the phone 360-902-3900 or off of their website. You will need your license number.
The letter from DOL should have informed you of the probationary dates. In any event, regardless of the exact date range you appear to be well within that 6 month period. You could likely avoid any problems by CONTESTING your new infraction and getting it dismissed, amended, or deferred. If you want to defer the ticket, ask for a CONTESTED HEARING instead of a mitigation. Remember, a deferred finding is not a right and a judge could deny your request for a deferral.
Given that you are facing a possible license suspension, it would be a good idea to hire an experience traffic ticket attorney to represent you. Feel free to call me at my office if you wouldl like to discuss your options further.
It starts from the date of the letter that you received. You need to contest the infraction instead of doing a mitigation hearing. You may still be eligible for a deferred finding at the contested hearing, if the Judge denies the deferred finding then you still have a chance to contest the ticket.