When did everyone start NST?

Courtney • First child beautiful son born 5/6/2015. Second son born 9/8/2016. Third son born 3/9/2018. Baby #4 heaven baby Sept 2018. Rainbow Twins due thanksgiving 2019!

When did everyone start having to have NST.

I know every doctor is different but trying to get a general idea of when they may start so I can think if my hubs will be able to attend or not.