well it took me about a week and a half
thats because when I had my 100k mile heads off, i had them flattened and a valve job done
I'd guess if you've never done it before (like me that time) it will take 8 hours start to finish. Just make sure you have everything so you dont have to run out to the parts store for stuff. Head gaskets, intake gaskets, RTV, thread sealer for the head bolts, good head bolts, a good torque wrench, fuel line disconnect tool (so you dont have to take the fuel rails off the intake)....
Spend a good amount of time scraping everything clean so you'll have good mating surfaces. It gets annoying fast but you'll thank yourself in the long run.
Dont rush it either, this is a very tedious job and you don't want to overlook anything by trying to get it done fast.
Take your time, especially the first time.
good luck