The section of the Momyer Creek trail that can be hard to follow is the section above the junction with the trail that connects the Momyer Creek trail to the old Falls Creek trail. From your described plan, you will not be on that section. The path you’ll follow from the Momyer Creek trail parking lot to High Meadow Springs is easy to follow. The trail is never steeper than 1,000 ft. of gain per mile, so it’s manageable by any hiker given adequate time.
The lower part of the Momyer Creek trail can be very hot this time of year, even pretty early in the morning, so either leave really early or expect it to be quite toasty for the first couple of miles.
Unless you were planning to go up to the divide from High Meadow, across the divide to where the Momyer Creek trail drops down between Anderson and San Bernardino East Peaks, your route will not include the section of Momyer that drops from the divide. If that was your plan, then be especially cautious on the way down. That section of trail is particularly easy to lose on the way down, especially if you haven’t already come up and and noted the places where the trail gets around the dozens of fallen trees blocking the actual trail.