Best suggestion leave it alone for 24 hours. This is from the support site.
If your phone number still doesn’t have a check next to it in Settings after 24 hours
It might take up to 24 hours for your carrier to verify your phone number with Apple. Contact your carrier to make sure that you can send and receive international SMS messages and wait up to 24 hours after you try the troubleshooting steps above.
If iMessage is on and a spinning gear appears next to your phone number, your device automatically attempts to verify your phone number. There is no need to repeatedly turn iMessage off and on.
Repeatedly toggleing may cause problems with activation.