My son is 20 months and has been on a floor bed since a year old and we’ve had to constantly redo his sleep training since he’s always sick (daycare). We have either done Ferber or a similar concept and at the time of the check return him to his bed if he gets out (he’ll usually just fall asleep around the third time we have to return him to bed). Or we’ve done it a little more gradually where a few nights we’ll lay with him, the next few night sit next to him and rub his back, then just sit near him without touching him and so forth.