Chaturanga, the yoga version of a push up is an extremely hard pose to master. It requires a fair amount of core strength and a ton of stability in the shoulder girdle. I often teach it by making students go from plank to chaturanga and then back to plank. If you are honest with yourself as you make the transition, you will know if you are actually ready for the vinyasa of moving to upward dog from chaturanga.
An easy way to monitor your progress in any plank variation is how level you can keep your head when you are in the pose. Very often, whether holding plank or moving towards the floor, the head will move at its own pace often dropping faster than the rest of the body. We are trying to avoid this at all costs.
Even if you don’t do yoga, I love all variations of plank for building core tone once the transverse abdominis is strong, and this is an excellent approach to bringing stability to the spine and trunk. This chaturanga preparatory pose is one of the first exercises I learned using blocks as a prop almost twenty years ago at Jivamukti Yoga Center on 2nd Avenue in Manhattan, not known as a bastion of an alignment based practice.
The game is to start with the block at its tallest and only move on when you can lower down with control, barely grazing the block and moving back up to plank with no loss in the solidity of the spine. If your upper back/body moves before/faster than the middle or lower back things are not going well. The spine needs to be rod straight to accomplish this correctly.
Once you master it with the block at the top height, lower the block one level, and when you can do that with ease bring it down to the lowest level, which to me, is as low as any chaturanga should ever go.