First I would select an MDM tool right off the bat. Preferably JAMF but one of the available tools out there as budget allows. I'm currently working in an all macOS/iOS environment and every day we wait to deploy an MDM solution the harder it gets because every device will have to be enrolled initially which, for us, means touching every device in the beginning. We hire 6-10 people a week so there are new Mac devices being added all the time.
I would also recommend figuring out what policies to implement as soon as possible as well. Firewall? Filevault? Software distribution? Anti-malware apps? Etc? I think getting all these decisions made up front will greatly reduce the headache as the admin. Getting everything settled in the beginning will make rolling things out much easier for all involved.
Also, enroll as an Apple Business Manager (or Apple School Manager) customer in the beginning as well. This will open up volume app deployment and DEP from the get go as well. I would say that simply having an Apple business account for purchasing product is not enough (as we only have at my company), go for the full Apple experience.
Hope this helps and good luck!
@edickson Thank you for taking a few moments to share some wisdom. It seems like we are on the right track. I am eager to see if anyone else chimes in.