Not receiving any mail.

Not receiving any mail.

New user here. Verified domain, added users, changed MX record and did email migration.I have not been able to receive any emails for the last 24 hours. 3 hours after changing MX record, I tried a few test emails but came back with instant failure. 24 hours after MX update, test emails are sent but I get no failures and emails are not delivered either.

What did I do wrong?

I changed the MX records before adding users, could that be it? If so, what is solution?
Should start anew? Any recommendations appreciated.