17. TIME PERIOD OFFER Purchaser and Seller understand and agree that, unless earlier withdrawn, this offer is good until a.m. p.m. The following answers to frequently asked questions may help you decide whether you should appeal your property's assessment and will guide you on how to do it.What are the address and hours of the Nassau County Clerk's Office? The Nassau County Clerk's Office is located at 240 Old Country Road, Mineola.