Follow -> DM -> Leadgen Question

Hi Community, 
I hope you are doing good!

I have a question about the following automation: 

1. Someone follows me
2. They get a DM from me (Thanks for following, as a part of the crew we would love to send you a freebie gift)
3. They hit the Button “Yes, sounds good!”
4. NOW I want another automation to begin, that collects the First Name and E-Mail Adress. However, the Follow DM option only lets me send a message (+link).

Question: When I have another automation going with the Trigger Phrase “Yes, sounds good!” - will it be activated? Or must the Trigger Phrase/Word be the FIRST message someone sends me via DM?

So basically:

DM Flow: Someone follows → DM → User sends “Yes, sounds good!”
Leadgen Flow: Trigger “Yes sounds good!” → Collect Data (E-Mail, First Name) → Send freebie via E-Mail

Thank you so much for your help!