Merging multiple tables

I have a number of tables I want to merge into a single master table. They currently all have a different structure but I could make them standard if needed.

Each row in all the tables has an email and a timestamp (and other information). I want to keep the “first instance” (oldest timestamp) and discard the other instances of that email if it comes up again.

Any easy way to accomplish this?

I can’t just insert into a master one table at a time because table B may have a record that is older than a record in table A…