Even if he did get (what seems to be) 50% custody - he'd have to include the days too and that probably won't work into his plans at all if he works full-time.
I was single as well when DS was born and there's NO way I would have allowed such an arrangement even if I hadn't have BF (I BF for 10 months). Young babies need one stable living environment, but he should of course visit regularly, take her to the park, pram walks etc.
DS is 2 now and I feel much more comfortable with him staying at his dads, but only one night at a time still at this stage although its usually just day visits still. He's happy to go and knows daddy well now so that gives me peace of mind.