Medical professionals will say NO, But if you notice his foreskin pulling back exposing the glans when you wipe his penis and tesicles during a nappy change there is no reason not to pull it back as far as you can get it and clean off the smegma that's visible using baby wipes this provents UTI'S provided he's not trying to grab the area and doesn't seem fazed by you doing this he won't mind you spending 2 minutes daily cleaning it for him or with him in the bath.

Just remember he may get an erection while doing it, as he gets older he will learn from you to do it himself, when you start doing it you will see parts of foreskin still attached to the glans these will go with daily cleaning and retraction of the foreskin, these are called adhesions and are normal until ages 5 or 6 they should be gone by age 16 but sometimes don't and need a medical professionals help to separate them.

Don't forget to pull the foreskin back over the glans to prevent a paraphimosis from happening.