When Josie started swim classes, the instructor had us put all our LO's in footie pajamas right in the water to help slow heat loss. The indoor pool temp was about 84F, which is frankly too cold for ME, let alone the LO's, but Josie actually prefers a bit of cold. (She did NOT get that from ME! LOL)
Definitely take it slow, but don't be afraid that he's too young. We waited till about a year with Josie, but with Nat (born in May instead of Jan) I have pics of her somewhere floating on her back in our bathtub at 7 weeks! (Wish to heck I could find that pic.
) We took her to the pool her first summer in just a swim diaper and rubber pants (required by our pool) as often as we could get her there awake (not as often as I would have liked LOL), as the outdoor pool water temp was easily 90F unless we'd had recent storms or cleaning/refilling with fresh water. We did keep it later in the day, like after 4 or even 5PM to avoid sunburn on brand-new skin outdoors, but it was SOOOO WARM it was worth the wait, especially since they were open till 9PM and we could stay till the kids were ready to drop!