When can i put my son in his bouncer?

My son is about 6 days old and I wanted to know if It is ok to put him in the bouncer. I have the fisher price precious planet giraffe bouncer with straps to hold him in. my pediatrician says 4months but i put him in it for a few minutes and he seems fine. it straps him in and he cant go any where. is there any risks with this?