How to RNG and delay bash script pressing RETURN for an autotyper script

Currently I'm using a bash script that automatically types out a phrase, but I wonder how to RNG the sleep counter for example to like 1800-1900 seconds. If possible I'd also like to know how to make the script delay pressing RETURN. Thanks.

this is the script

#!/usr/bin/env bash
function autotype_loop()  {
xdotool key space
xdotool type "Text here"
xdotool key Return
sleep 1810
autotype_loop
}
autotype_loop