TSA-Precheck

quick question about TSA-Precheck. how does it work and when i mean by that. will my ktn# be on my boarding pass if i order happen to order my ticket first and forget to add KTN# to my DA account.

short story: bought my ticket ,but forgot to add my KTN# on my delta airline account before buying the ticket and wanted to make sure it was on it. \*noted\* did add it later on to account ,but will it be on the ticket though?