I read when I had DD that you should avoid products that have enzymes (eg. BioZet) though I have no idea why, so used what I think was then called Amolin, now called "Purity" until she was about 6 months when I put hers in with ours (use Earth Choice normally which is not very harsh anyhow). I also used a baby/sensitive napisan.
This time I'm sure bub will get exposed to some BioZet as it's the only thing that works on DH's work clothes, so there'll certainly be some residue in the machine at times. Hoping he has non-sensitive skin like DD!