Just a thought, 8 weeks and 12 weeks were at 9 and 13 as we couldn't make the 8 week one, plus they had no space.
However Ive just realised the 16 week one is when he's 16 weeks so will be 3 weeks after the 12 weeks rather than 4.
Does it matter? I know some do need to be appropriately spaced but not sure which.
Might phone hv but they're hard to get through to sometimes.