Congratulations! It looks as though your little one will be oop pretty soon! It is safe to go ahead and get him neutered now. Doing so will not interfere with his daddy duties.
Just make sure that you do keep a close eye on him for the first 24 hours post-neuter to make sure that he is healing well and mommy isn't going to try and groom him around his surgical area.
If you do a poms on, his recovery would be pretty quick, usually within 24-48 hours if all is well, he will be good. If you opt for poms off, he should be separated from mommy for about a week in order to give the site time to heal over.