The shortcuts (M1, M2, M3...) are NOT scripts you must follow. They are just ideas to help you keep the conversation going after a sub replies to the mass message. They often fit well and save you time, which is great. BUT they are not a free pass to turn your brain off. Like with any shortcut: stay awake, think for yourself, and decide if it fits, or if you should start the conversation your own way.
The moment a sub replies, ask yourself: is this sub ready for selling or not?
Quick check trick: early on, ask "hey, do you have time right now?" This tells you which way to go.
Read the sub first. Look at what kind of sub he is:
Based on that, pick your angle:
How you go into the conversation after the MM depends fully on the sub: who he is, his mood, and if he has time right now or not.
One last thing: if a sub is busy or distant, do NOT force a sexting attempt. A failed attempt lowers your value with him. He won't notice it consciously, but the connection takes a hit. When in doubt, pivot to something light (a personal question, a small game) and sell another day.