that should be "1,001" or "10,001"

Just briefly my thoughts on this (I'm travelling at the moment):
Limit 100 means that you only get 100 records back. So the last one is record no. 99.
The start at index 0 has the decisive advantage that you can use the start and limit for all loops with a loop variable.
steps = 100 #constant
loops = 0 #increase after each loop
start = steps * loops
limit = steps

Unfortunately I can't test your script at the moment. ☀️