With the extreme issues I had with my first, my goal was a day by day prospect. She was never breastfed, but was bottlefed EBM. I would not recommend full time expressing to anyone..ever. I made it until 8.5 months and fell pregnant with no.2 and could not maintain supply.
My goal with no.2 was 2 years. I weaned at almost 3yo because I was so over it.