Did I set the trailing stop loss order wrong? TD Ameritrade

I have an IRA with TD Ameritrade, and it's been a while since I've invested.

I bought VTI a week ago with a market order. I then submited a trailing stop loss order after with a trigger of 8%.

I'm starting to think I was supposed to submit my BUY order as a trailing stop loss order with 8% and that I went about this all wrong.