We dropped it when Violet stopped taking it (which is about a month ago).
We used to give her 5oz but she'd only take 4oz so we dropped to that and gave her that until she stopped taking 4oz. She'd start only taking 3oz's for a good few weeks so then we dropped to 3oz as it was a waste doing more. Then again, she stopped taking as much for a few weeks so we dropped an oz again and then again until we just stopped giving her a bottle.
She did start wanting a little bit more during her day feeds tho, she has 4 bottles during the day and they each went up by about an oz.
We just followed her and she's fine, sleeps thro for easily 12hrs at a time and is very content during the day. We're BLW and she's not swallowing anything properly yet but she's fine. HV is v.happy with the amount of milk she's getting so I'm not going to 'force' her to have a dreamfeed, following the same principal as BLW with her milk feeds - let her decide if/when/how much she wants.