The three pints over a couple of hours wouldn't actually bother me, unless he's noticeably wobbly after that much.
But I'd expect him to put the lid on it at that point, because he must know you'll be worrying about dd whilst you're out. If he carries on drinking, & you know he is, then even if you do decide to trust him, it's inevitably going to put a dampener on your night out.
Almost as if he set out to spoil your night...? Because it's much more convenient for his 'me time' if you'd rather be at home than out & about yourself...
Not saying he'd do so deliberately, but, well, does he normally have 3 pints at tea-time on a Friday?
Because if not, it would definitely suggest to me a spot of 'accidental' sabotage, or at least him sending out a 'Friday night is BLOKE drinking night, & you should be glad I came home at all, actually' vibe.
Definitely you need to sit him down & have it out with him (when he's sober).
How would he feel if you chugged a bottle of wine whilst looking after dd? Would he see it as perfectly reasonable ( he just doesn't 'get it' about looking after babies, & needs it spelling out), or would he disapprove (in which case he knows damn well he's out of order!).