Delaying nursery start date until after mortgage

We have a mortgage and are looking to relocate when our fixed term ends in April next year. We have two children, a two year old who is at nursery and a 6 month old that is due to start in Feb - she'll be 11 months old at that point. When our youngest starts nursery our childcare costs will effectively double.

We felt that our eldest really only started to benefit from nursery when he was about 18 months.

Is it worth postponing our youngest's nursery start until after we move? Looking at this from a maximising how much we can borrow perspective.

For context, my wife went self employed just over a year ago and only has a half year's worth of tax returns as she's been on maternity as well. She has a bunch of retained clients waiting for her to go back full time so we aren't concerned about future affordability. This means lenders effectively basing our affordability on just my salary. As a result we are cutting costs as much as we can.