If you are ready to lock your pool and show numbers you can go to the settings (gear) on your grid.
From there, you can toggle on "Show Axis now and Lock Grid".
Keep in mind that this will populate the numbers and members will see them. You cannot change it once locked.
Note:
This automatically happens when the event your grid is for begins. However, if your grid fills early or you know you will be getting no more squares filled, you can use this option.