Mariella wouldn't sleep during the day unless she was in my arms up until i'd say almost 4 months, so not too long ago.
Actually she really wouldn't do anything except scream if she wasn't held
I sometimes tried to put her down somewhere else, and having her fall asleep there, it worked maybe a handful of times.
I got the "you're spoiling her" "she needs to learn to sleep on her own" etc all the time even from her dr. But i went with what she needed and every now and then tried to put her down in her crib but never forced it.
Then around 3/4 weeks ago it was like something clicked and she was out of her colicky-ness and didn't sleep very well in my arms anymore, and slept well in her crib. Now she's actually a decent napper, we usually get three 1 - 2 hour naps during the day. It has to be pitch black dark and silent though now.
She does also sleep in her pram or car seat, but those sleeps aren't as long or deep or restorative, which is why i try to be home for all three naps most days and if not then only have one "on the go" nap. It is limiting, but i'm not as limited as I was when she was screaming all the time so it's a total improvement for me haha
What i will say is though when my baby sleeps, then only where she fell asleep in the first place. There's no putting her down asleep, she wakes up immediately.
So in my experience, at that age, don't worry about setting bad sleeping habits. If he is fine in the night then it shows he actually can fall and stay asleep. Daytime sleep is harder for them but he will get it in time!
Mariella was the same, wonderful at night so i knew she'd get there during the days eventually and she now has.