Exchange Migrate Sequence

[CJake]

Hi Everyone, 

We have a Exchange environment which we want to migrate from 2013 to 2019. We have Edge Server as well.

I would like to know the sequence of the migration. Can I start with migrating Edge role first while keeping 2013 Mailbox Servers or do I need to start with Mailbox and then the Edge?

TIA

[#2]

You can use the Deployment Assistant for Exchange and select the option that you have an existing Edge Transport server deployed. This should give you some direction. Personally I don't think it really matters.
https://setup.microsoft.com/exchange/deployment-assistant

[#3]

@Dan Snape 

After you complete the Mailbox server, configure Edge.