We gave one at about 4.5 months when we took his paci away. Ous is a little elephant with a soft blanket attached, I don't think it was big enough to cause problems as he could move his head well by then. We also started weaning the swaddle at that time by releasing one arm then the other so he could hold the lovie!
I would say if you do introduce it buy extra ones - we currently have 3 on the go in his cot. one hidden in a drawer, one at grandma's and one at nursery
. I can however take the cot ones away one at a time for washing!
HTH!
Laura