you should have applied at least 3 months before you EAD expires. just in case they don' approve by 90 days, you can get an interim EAD by walk-in.
for now, you can either apply online at uscis.gov (it will go to National Benefit Center) or apply by paper to where you 485 is.
both methods have their own advantages and disadvantages. the good thing about online app is you get your receipt right away. don't have to wait for receipt # in mail. but you need to go to application center to finger print. if you apply by paper, you don't need finger prints. sometimes it is faster. but i am not sure.
you can do a search on EAD in the forum. there are a lot of useful information in the forum. the sooner the better. apply today!!!
