why is it taking long for my phone number to connect to imessage?

Here are the basic instructions:

iOS and OS X: Link your phone number and Apple ID for use with FaceTime and iMessage - Apple Support

You may do well turning off other iMessage devices while linking your phone number to one device at a time.

sign out of facetime and imessage

• Settings > Messages > Send & Receive. Tap your Apple ID, then tap Sign Out.
• Settings > FaceTime. Tap your Apple ID, then tap Sign Out.

restart and sign back in

if that does not work, try to

turn of imessage

turn off facetime

restart the phone

turn both back on and wait for activation

if that does not work, try to reset network settings, reconnect to wifi and try again