When i first got my babies I was afraid of them sleeping on the bed too. Rocky's 5.9lbs and he sleeps on the bed every night, my fiance is afraid he'll roll overhim so he sleeps on my side, and he does o.k. He has fallen off the bed before, not because of us, but he'll be rolling around or whatever and fell, but he never got hurt. Bella is 3.5lbs and she was sleeping on our bed until we found out she was peeing under the bed in the middle of the night
But she always did o.k. She would sleep right by my stomach and never fell off or got rolled over. I would wait until maybe your puppy is another lb or so, and it also depends on how "durable" your puppy is. Rocky and Bella both seem pretty strong, that's another reason I allow them on the bed, so if they do fall, like Rocky has, I know their O.K.