If your frame rate is 60, then a 60 * delta in the
fixed_process is going to be 1. Anything times 1 is the same. So I don't think you need that.
Also if you have the timer's wait time being set in the
fixed_process isn't it getting reset faster than it can expire? Fixed process at 60FPS is going to execute once every 16.6 milliseconds.
I would think that you want to set the wait time out in the
ready function, and then again at the end of the timer time out.
If you want to used
fixed_process you should want to just drop the timer entirely, and keep a counting variable and use an if statement to track the intervals.