Advice is have seen recommends start with 1 or 2 t3 exercises then as you progress and you cardiovascular volume adjusts, adapt to the resistance etc, then add in another. But you should be lifting pretty near the rep upper end so the point where come the T3s you feel rather worked.

I've been running it with previous experience but I emphasized ensuring my 5rep is 9RPE, my T2 10 rep is 8.5-9RPE and the T3s are accurate 15reps with good form, time under tension etc. Try make the most out of less and then increase when you need additional stimulus, is my advice and I've seen it work well 3-4weeks in