Sure 5oz tomorrow is a move in the right direction. If she drains maybe keep to 5oz the following night too, then drop to 4oz. (just think if you drop an oz every 2 days there's only 8 days to go before the bottle is gone - not long at all)
Remember it's ok for her milk intake to drop some at this age and that she might add to her morning milk if she needs too. It's a good thing to take on milk/water a little earlier in the day, not that you are pushing for night dryness but just in terms of it being a bonus to create that habit for the future when PTing comes along.
Sounds like it's going well.
When my LO is teething or has a cold he appears to drink more, sometimes even just before bed, so that extra water in the afternoon could well have been teething or maybe something in her solids was a little more salty.
