Lately I have found that I need a better system of reminding myself about time sensitive tasks. So after some searching and testing, I have found this solution. The solution is a Cron Job with the notify-send tool. This is particularly useful using Gnome 3.
First run the command crontab -e to in a terminal to edit your cron jobs.
You should now be using VI to edit your Cron Jobs.
Press i you are now in insert mode
Then add a line similar to the one below.
0-30/10 13 * * 1-5 DISPLAY=:0.0 notify-send Test “Hello”
The above line adds a notification entitled Test with the message Hello. It also starts notifying you ever 10 minutes from 1:00PM to 1:30PM daily. Just delete the line if you do not want it to continue.
Then save and exit, your VI session. Press Esc then type :wq and press Enter.