u/Calm-Ad1924

I have started training for my first triathlon and I have question about the bike fit. I have a decent road bike that I plan to use but I want to get clip on aero extensions for it. I would also like to get a bike fit very soon. Should I purchase the aero bars before the bike fit or is that something they will help me figure out at the bike fit?

Also open to suggestions on brand/model of clip on bars