I am a general contractor and want to place a lien. I may have not sent the 20days notice to the lender. However the job is not completed and the customer may be in process of refinancing . Would a 20day notice to renew lender would protect my previous unpaid fees and cost?

Want to place a lien but may have not sent the 20 days notice to the present lender. The comany that i did the work for is about to refinance with a new lender. I have giving the notice to the comany but am not sure that, they have sent it to the lender. During the course of construction almost two and half years ( six month project) they have delayed payment by months at times. I want to place the lien regardless. However if i do place a lien after refinancing by the customer would that have any effect. Thank you!