Extraction mechanic help with geckolib

I'm trying to make Dandy's world mod for minecraft java (Neoforge if that's important), and i wanted to make so that when mob from my mod (Toon) will be close to a machine it will play an geckolib extraction animation for as long as toon stays there. Machine is a double block and i would want for as long as toon will be 'extracting' it the bottom part of the machine will change to another block and after some time the upper half will change, the time needed to fully change the machine original blocks will be different for each specific mob. Can you please give me the procedures needed and where do i put them? If you can i would also appreciate a procedure example for my mobs so they would be staying near the machine untill it's filled or they're being chased by hostile mob.