I don't think letting baby cry when they wake up helps - it just further wakes them up rather than helping get back into a deep sleep.
Why did you walk away if baby wasn't settled?
Babies do need actively helping to get to sleep. It needs some work and effort. If you just left him to his own devices I'm not surprised he woke up fully and started playing - babies don't inherently know they need to go to sleep. Neither do they automatically know how to do this, how to go to sleep. You have to stay and teach them.
If this was my child, firstly - the "bedtime" you mention. I assume you mean when you went to bed? Say 11pm. Due to NHS SIDS advice, and also because of the nature of baby sleep, putting baby to sleep for "bedtime" (say 7-8pm) would mean putting baby in bouncy chair downstairs for another daytime nap. Because the nap cycles do generally carry on later until baby is a little older, so waking after 45 mins (as a nap) is normal and to be expected.
So I wouldn't be surprised by a 45 min or so wake up after an early evening bedtime. Just keep awake time minimal at this wake up. So feed, wind, cuddle and back into bouncer. You might even get two "naps" between a 7pm bedtime and you going to bed and taking baby with you later in the evening.
Your expectations are unrealistic if you're expecting something else. Maybe adjust your expectations?
Then dealing with any wake up, again if it was my child, I wouldn't be wanting any crying. The quicker and more effectively I respond to baby, the quicker and easier resettling is. Once you get to the point of baby crying, I'd accept that extra help is going to be needed to re-settle. I certainly wouldn't just put dummy in and leave.
My escalation of help to get baby to sleep at night involves:
- Dummy
- Dummy tap
- Shift my upper body from my bed to lie inside the sidecar cot, Cuddle up close to baby, encircling. Hand on chest (and continuing dummy taps as needed)
- If baby starts kicking and thrashing, then use my body and hands to still limbs to keep baby still, while simultaneously keeping baby quiet by actively sucking the dummy. AS long as baby is still and not crying, just stay there cuddled close and often falling asleep myself and just wait. Then extract myself once baby is asleep (or just stay asleep there, as was often the case)
- If baby is crying and not wanting to settle - something is wrong and extra help needed. I'd be picking baby up and seeing what was wrong. Often it would be wind. The cuddle itself might calm an upset baby, and winding while cuddling may also help. It's about calming baby enough so that the ladder of steps above do work - so an in cot cuddle and active dummy sucking calm helps baby relax.
- Might be hunger. Usually it is hunger if nothing else works and no burp is forthcoming. So a feed is a last resort to settle baby.
- Occasionally it could be that baby is overtired after a bad day, or maybe pain, so some extra help is needed to calm baby enough to be able to relax and go to sleep.