Exhaust repair tape?

So here’s the situation:

I hacksawed the battered up muffler joiner coupling and bought a general exhaust pipe joiner and bolted it on.. Well it started to leak from the seam where the joiner clamps down in both ends.. So i filled the holes with exhaust paste and heatgunned them dry.. After i started up the car, the exhaust paste just flew off like it was nothing..

Well i reapplied the muffler paste but this time i put the tube right against the hole and squeezed it so it started to splurt out on the sides so i know the hole is now properly filled up..

As a “insurance” i wrapped both ends with exhaust repair tape to make sure that the exhaust paste has nowhere to “fly off to” as the tape should stop it there.. Then i took a heatgun and warmed the tape up so it got sticky.. Then i used thick gloves to mush the tape together so it makes a very tight seal around the pipe.. Now the tape is only semi hard and it gets mushy and appliable after reheating it.. But i know the paste is hardening inside..

I haven’t started the car yet because i don’t want it to fly off again.. How long should i wait for it to harden up until i start the car up to “finish the process”? I already took a heatgun to it and got it semi hard around the pipe.. The package has NO instructions.. It only says: put the tape on, then put aluminium tape around the tape and then secure it in place with metal wire.. Then start the car and let it harden.. Then remove the tapes.. (Exhaust heat finishes the process to harden it)
I think a heatgun should be sufficient enough though?

The exhaust tape had a fiber to it and it pretty much doesn’t stick to anything or itself. But once it’s heated up, it turns into a black tar-like substance. Then it hardens like stone.

So my question after explaining the situation is: Should i start the car now and check for leaks or wait till the tape and paste hardens over night and start it tomorrow?