J.ustahand.
I feel for you. Been there myself a couple of times.
First thing, yes contact a good business lawyer and even he will likely refer you to an attorney who specializes in filing leins. Do not attempt to file one yourself. If you misspell something or make an error in punctuation it will be thrown out.
Secondly, I believe you will need to do this in the area where the work was performed since you are leining an asset (equipment,,facilities, etc) not the company itself.
For what its worth I only started this after the thirty day mark but it all depends on your terms. My invoices gave customers thirty to pay. But, you may start anytime you feel you no longer stand a reasonable chance of collecting. If however you wait more than 120 days, you are out of luck. Statute of limitations expires and you will have very little recourse beyond this point.
Hope some of this helps. I'll check back on this post and see if I can be of any further assistance.
GH Weidman