Federal Withholding - First Time

Hello - had a quick question about a young adult entering the workforce and federal withholding options

The young adult may work one job early in the year and another job later in the year  (or multiple part time jobs concurrently) and will exceed the standard deduction in ~Q3 of the year

 

For federal withholding, is it ok to start this later in the year when we get closer to the threshold, or are we required to start 1/1 ?  thanks again for the help !