What kind of validation do you need to do? In case of checking that entered number is between a specific range or checking that date is not in the past, this can be done before record is inserted, however if you need to check that value is unique in the datapage, this can be done only when record is inserted. You may also conciser creating a two step registration - create a submission form with only main fields which control uniqueness and then entering other info on update form.
You may find more details here and here
Hope that helps.