How to avoid to start hundreds of threads when starting (very short) actions at different timings in the future

I use this method to launch a few dozains (less than thousand) of calls of do_it at different timings in the future:

import threading
timers = []
while True:
    for i in range(20):
        t = threading.Timer(i * 0.010, do_it, [i])    # I pass the parameter i to function do_it
        t.start()
        timers.append(t)  # so that they can be cancelled if needed
    wait_for_something_else() # this can last from 5 ms to 20 seconds

The runtime of each do_it call is very fast (much less than 0.1 ms) and non-blocking. I would like to avoid spawning hundreds of new threads for such a simple task.

How could I do this with only one additional thread for all do_it calls?

Is there a simple way to do this with Python, without third party library and only standard library?

from How to avoid to start hundreds of threads when starting (very short) actions at different timings in the future