Well, I guess it depends on what those additional steps are, and why it’s important to you that Nextcloud is not reachable until those steps are completed.
If those steps are occ commands, then Nextcloud needs to be functional in order to be able to run them, so it would make sense to check that all containers are up and running, and that it is reachable at that point. 
If for some reason you need it to be completely unreachable while the occ commands are running, you could perhaps block incoming network traffic or stop the web server service.