New build payment- within 5 days?

[Fedupofallthemud]

Is it normal to have to pay full price of new house within 5 days of completion certificate being offered?
This seems very tight to me, but maybe normal?
Anyone who's recently been through this your comments would be appreciated

Oh! I thought it was sensible/advisable to retain 10 - 20 % for snagging. So you keep some back and only pay it after a few months, when you are sure all is well.

Maybe that is what the 5 day period is??

www.watsons-property.co.uk/new-build-snagging-reports