I'm sorry but there are too many factors involved to "set a time", the server should be the biggest time killer, depending on what server you will be using. Ex. Window 2000 Server, if you are configuring a Domain, Policies, Active Directory, OU structures, User accounts, printers, You can have 2 guys speading 25 hours on this alone.
Workstations are pretty much straight forward, until you get into restrictions, usually installing from CD, SPs, critical updates, apps, I would guess 3-4 hours on each one, gotta love the reboots.
A+ will help, but it does not teach you very much about setting up domains, policies, for that you will have to take server courses, serveral courses, that is why the MCSE exam is 7 parts, recommended that you have 2 or more years in the field first. Don't get me wrong, alot of companies are happy to have a A+ cert on hand.