This is adorable!! The only edits I would do (personally) would be to try and match color & exposure of photos more. The newborn pic is a little dark - I would just lighten it up a tad. And the last photo is a little orange compared to the others - I'd try to lessen that a bit. It's a trick I've done to series of photos from different ages - I always try to make them similar so that your eyes don't get drawn to the one's that have different color and/or exposure
Other than that I think you did a fab job!! It's adorable - HE'S adorable!!!
I love the kit you used - it really works great for a bday invite