I almost thought it is impossible to unswaddle my baby because his reflex is super bad. So he went for his vaccination at around 3.5months, at night he was drowsy, sleepy and feverish. So we thought might as well we take this opportunity to stop swaddling for the night as we are afraid we will overheat him, furthermore he was quite drowsy and sleepy so his sleepiness will mask the reflex. Indeed he sleep through and successfully transit him out of swaddle
You can still swaddle your baby. As long as your baby is comfortable or when baby start to flip you can stop.
I stopped at 4.5 months when my LO kept flipping onto her tummy
gwerlin