So, I have the code P0715 code with the sometimes not engaging in gear and RMPs going up and other times just rough gear shifting issue. I did the dielectric greace to the TCM first. Now I have made my home made transmission fluid level dipstick

I DO NOT have an IR temp tool. So I can't check it at 80*C. But my question is if I just go out and start the car and then put it in drive and check the level, is it safe to assume that is an accurate cold level?
And if so, and it looks correct there, is that a good enough guage that fluid is NOT low?
Or is it necessary to check it at the 80* temp also?
I have read the several posts re: this issue over and over but dont seem to see whether
both readings are necessary or not....
Please and thank you