Does anyone know whether I should top or fim?
Hello - Welcome to AFN!

You could top or fim. It depends on how old the plant is, and to some degree the genetics .. but most modern autoflowers can take a topping (advised at the 4th note - day 15-20 for an autoflower)
There's a topping thread from autobeast that worth reading

Auto topping thread,pushing the auto limits;)
Good day growers im a master photo and auto grower.but my passion is with autoflower seeds.i been on a mission for 5 years growing now trying diffrent methods of training on autos to see what they truly behold.truth is autos aint no diffrent to a normal plant other than they flower on there...

Hope this helps
Blue ^_^