DS wasn't a fan for quite awhile too. I would just do it after I changed his nappy and chat away to him. As soon as he got sick of it, it was over and done with. When he was about Isla's age though, somebody showed me how to fold his arms underneath him (so he was resting on his arms like you or I would iykwim?) and that made all the difference. He really started to enjoy and would be happy on his tummy for a minute of two. Apparently you're meant to do it that way to begin with Anyway, that made the difference for us so might be worth a try.

Personally I don't think it's a big deal... I took the attitude that we would try it several times a day and if we only go 10 or 15 seconds then that was ok. Oh and BTW DS was a good 4 months before he started rolling - I think 3 months is pretty early. HTH