I have a simulation where I have to make sure that all users have ramped up to a certain point in my scenario and only than continue (all users at once)
and execute the rest of the scenario. Is there any way to do that?
Sounds like the rendezVous might be what you are looking for! 
https://gatling.io/docs/current/general/scenario/#rendezvous
But you have to configure the number of users to wait. It can’t be inferred from the injection profile as you have no idea how many users will be started with a closed workload model.
Thank you!
Stephane, can we set up multiple rendezvous points within a scenario?
Yes. just that each rendezVous has a one-shot usage atm.