I'm a total novice and my DD is about 6months younger, but we've been having success with eliminating night waking and early wakings by using a later bedtime. I know those can be signs of overtired, but in our case we were putting her to bed to early and she wouldn't be tired enough to sleep for a long time (but tired enough to fall asleep). She'd wake many times overnight and start her day at 6am-ish. Because she didn't sleep well, she was a total crank-pot and would want a nap by 9am and then another in the early afternoon (both were short usually) and then we'd put her to bed early cuz she hadn't napped well. We didn't know what to do and I kept adjusting the bedtime earlier and earlier to compensate, but we didn't get results.
We had family in town and DD was so intrigued that there was NO way she was going to bed at 6:30pm...she was staying up until almost 8pm! We had fewer night wakings and later mornings. She is also usually napping better during the day. Hmmmm...so even though family is gone now, we're shooting for a later bedtime (sometimes have to bring the dog in to entertain her, sometimes we go for a walk around the yard or the house or anything that we think will keep those peepers open just a wee bit longer!) and we are having fewer night wakings. We do still give DD a bottle around 5am-ish and that seems to tide her over til the 7am hour, but she's a picky and very light eater so I actually think she wants/needs that bottle. We still have some wonky naps these days, but I do think we're in the midst of a 2-1 nap transition so that's normal.
Not sure what the average for a 19MO is, but read the other day that a 13MO averages 11 hours overnight and 2.25hrs during the day with 2 naps. At 18MO, I think the numbers are similar but only 1 nap during the day. Perhaps tackling that transition to 1 nap might get James a good rest during the day and able to last a bit longer for a later bedtime. It improved things for us - it's not perfect mind you, but definitly an improvement.
Good luck!