At what age do you think we should do our CPF nomination. And how important is it when it comes to retirement planning?

We should do a CPF nomination now so that our money would go to only the intended people. We do not know what is going to happen in the future.

This will be part of estate planning (how to distribute your assets), rather than retirement planning. Although consideration can be given to estate planning during retirement planning.

Nominate now if you have the time. And again after u are married. (If divorced, nominate again) Then again when your children are of adulthood.

The nomination becomes void upon marriage and remarriage. Nomination is NOT voided upon divorce, so one might want to renominate unless they which to give their ex-spouse the money.