At 12 months, anywhere from 20-40 mins for naps and nighttime settling. He would dream feed a few times over the course of the night without really waking.
Now, at 20 months, 10-25 mins at nap and nighttime, usually ~15. It gets better. We still nurse ~3-4x/night, but he falls back asleep right away. He has always woken at least once mid-nap and nurses back to sleep after 10ish mins.
I, personally, would maintain the nursing to sleep association. It's so gentle and nurturing, and this time disappears. DS is nearing 2 (!) and Incant believe how the time has flown. The frustrations and difficulties are far outweighed by your satisfaction at maintaining an intensive breastfeeding relationship in hindsight. Nursing-- and night nursing-- my toddler son has been the beautiful reward for the first year's hiccups. Trust me, the best is yet to come. You don't want to deprive either of you of the fun and loving times ahead of you.