I think you can work on shifting bedtime in increments if you want to shift BT and WU time, and keep total night sleep the same, but to get on top of OT, it's better to do a shift in one go to see if getting a shorter day helps get his routine back on track. The idea is that some LOs tack on sleep at the beginning of the night, so you put them to bed earlier, they get the extra sleep in the evening and then wake up at the same time in the morning, resulting in more sleep overall.
An EBT can be useful to keep on top of OT if you've had a day of short naps, but it's more something you'd do every now and again to see if it helps. I appreciate it's tricky to reduce day length when you're not getting long enough nights, but sometimes an EBT can reset a LO by getting one good night in...