Hi
My DS is almost 4.5yo and still has a big milk drink in the morning, around 150 - 200ml and still takes a good breakfast.
This is from the NHS site
Children between the ages of one and three need to have around 350mg of calcium a day. About 300ml of milk (just over half a pint) would provide this.
My approach is that one good milk drink (like the 200ml your LO is having at WU) meets most of her daily dairy needs, and the rest you know will come from cheese, yoghurt etc. I actually wouldn't rush to cut the milk drinks too low as she'd need to have lots of dairy solids then to get her needs met. If she wasn't taking a good breakfast I'd be tempted reduce or cut the morning milk but keep a milk drink somewhere else in the regular routine.
I personally think it's easier to keep either a morning or evening milk just because your' more likely to be home and have easier access to milk at those times but it's really personal preference.
I dropped the BT bottle at 12 months. Again it's personal choice and I chose to keep the WU milk. I don't think there is a 'usual' time for dropping that milk, just whenever you or LO chooses to drop it. I would say though that you need to put teeth brushing between the milk and sleep if you are going to continue with an evening milk. This was one of the reasons I chose to drop the BT milk and keep the morning milk, I knew I had to change our routine to put teeth brushing between E and S so I introduced a sippy of milk with a solids supper before bath time (as you said, a bit of a top up after dinner) and did a gradual wean of the BT milk/bottle.
Everyone is different and for different reasons.