I just use target ones. I use them with long sleeves in the really cold nights and no sleeves when it's a bit warmer but still cool. When it's over about 15 degrees overnight I just have DD in a jumpsuit or flannel PJ's and don't worry about a sleeping bag and she's fine but she's a bit older than your bub. I think once the really hot nights hit I'll probably just leave her in a singlet and nappy and that will be it for hot nights.