Beckham should be a Saint by Wed and on the practice field by Thursday giving him two days of practice to carve out a limited role while they get him up to speed.
I don’t know how quick a learner he is but it took Emmanuel Sanders a couple weeks to settle in even as a vet. Beckham potentially can provide a little more athletic juice but a 10 catch 100 yd game after 3 days as a Saint would seem like a stretch.
4 catches for 50 yards and a td is doable Tho