Schedule mail to send in future in Gmail

Hi friend..
i am here again with a new trick
you can schedule mail to send in future
go here and install extension for firefox
it will look like this-

than install it
it will look like this

than you get a message to restart firefox

now open gmail
and than compose mail
than you will get a tour of boomerang

than click start
than next

than again next

than finish

now you will see a your compose mail page like this-

now write a simple mail and select time to send it
like this

now you have done..
Cheers!!!