I am not an expert, so I won't tell you any more than what I know - in other words, this information is not complete, but I have included some good links:

FIV is not readily spread, and the transmission agent is saliva. The virus does not live long outside the host so it is extremely unlikely that a cat can pick it up from a blanket, for instance, that another cat has chewed on. As far as is now known, the only way for cats to spread it is through bites. Here's a good link:
http://web.vet.cornell.edu/Public/FHC/fiv.html

FeLV, however, is spread through other bodily secretions as well as saliva, so it is much more contagious, as cats who groom each other, sneeze on each other, or share bowls will likely transmit it to each other. Here is a good link for it:
http://web.vet.cornell.edu/Public/FHC/felv.html

As far as the waiting period, it would really depend on which test he was initially given, as you may have read in the link. Of course, if you want to retest sooner because you want a second opinion, I wouldn't wait at all.

[This message has been edited by 4 feline house (edited March 28, 2001).]