This one is interesting because spacing out the vaccines will reduce the fraction of children who actually go through with getting all their vaccinations and therefore have a net negative effect on public health, but at the same time I personally wouldn't agree to get more than one vaccine in the same day. I recall getting rather sick after getting multiple vaccines at the same time when I was a child. (It wasn't life-threatening, but it was quite unpleasant for several days.) And even now, the last time I got a covid booster I was in bed for two days afterwards. I wouldn't want to potentially compound that reaction. A relative of mine recently insisted on spacing out all her child's vaccines and that's what I would do if I had the time and money for the additional visits to the doctor.