I suppose it depends how big you want it to be. At the moment it looks very healthy and lush, but if it starts to look unhappy, then re-pot it.

I used to move mine outside in the summer and it loved it - grew enormously each year. In the end it was too large to continue to do this and it had to stay outside. It survived a couple of winters wrapped up on a verandah but sadly finally succumbed to a very hard winter.

It lived for about eight years altogether. No avocados though....