Default rooting

Hi

I am going to root my G2 for the first time. its currently on stock jellybean.

I would like to know if I should root now on jelly bean and install a custom rom or upgrade to stock kitkat first and then root?

if I am going to a kitkat custom rom would it make more sense to upgrade to stock kit kat first or is it easier to root from jellybean?

What are the advantages/disadvantages of either?