Why do my iMessages take a long time to notify me on my iPhone?

I have an iPod and a iPhone both linked up to iMessage with the same number. But with my iPod I can only chat with purely iMessage.

I have noticed that my iPod dings instantly when an iMessage has been sent to it. But my iPhone however, doesn't give me a notification until 3 to 20 minutes later.

This situation bugs me a lot and I was hoping for a way to fix it.

I tried turning off iMessage on my iPod along with turning it off but my iPhone still receives it very late.

Any solutions or other experiences will help.

Maybe your Wi-Fi is messed up try taking it to the apple store to sort this issue out