Stop using SNOO by six months, or sooner if your baby reaches a weight or developmental limit. Being small enough to fit doesn't mean they can stay in it longer.
We used ours all the way up to six months, then had a panicked transition to the crib. We never used Weaning Mode, and we started letting her arms out late.
The stopping points
Happiest Baby's guidance gives six months as the age limit and 25 pounds as the upper weight limit. Stop sooner if your baby can push up on their hands and knees.
Their published product instructions also say to stop if your baby can sit, kneel or pull themselves up in SNOO. Consistent rolling is another limit, explained below.
You don't need to reach all of these at once. A younger baby who reaches a stopping point needs to move out too. And if any part of the SNOO is broken or damaged, stop using it until it's resolved.
What about rolling?
The clips don't mean rolling can be ignored. Happiest Baby's instructions say SNOO is for babies who cannot yet roll consistently. They define that as rolling from stomach to back during sleep on multiple occasions.
In a crib, the AAP says to stop swaddling as soon as your baby shows signs of trying to roll. Don't carry the SNOO swaddling routine over into the crib with their arms restrained.
What our transition was actually like
We didn't have a gradual plan. We got to six months and had to make the move.
The arms were a big adjustment. Our baby kept rubbing her face, knocking her pacifier out of her mouth, then yelling herself awake. We started arms out late, so that was still an issue during the transition.
We can't say whether Weaning Mode would have helped because we didn't try it.
If you want to try Weaning Mode
Happiest Baby suggests practicing with one arm out, then both. Once that's going well, they suggest about one to two weeks in Weaning Mode before moving to the crib.
It keeps the white noise on without constant rocking. Motion can still come back when your baby cries. The setting is under Modes in the app.
The Weaning setting. We left it off.
Our Weaning Mode guide covers the settings and Premium access. Don't keep using SNOO past a stopping point just to finish a weaning schedule.
Moving to the crib
Use the crib's own firm, flat mattress with a fitted sheet. Leave out pillows, loose blankets, bumpers and toys, and put your baby down on their back. If they can roll both ways on their own, you don't need to keep turning them back. These are the AAP's crib sleep recommendations.
Moving to a crib doesn't have to mean moving to a separate room. The AAP recommends sharing a room, but not a bed, for at least the first six months.
For how we ended up with a SNOO in the first place, read our first three months with a newborn.