Chaturanga - pin your elbows to your side. Once you get down about halfway to where you elbows are pressed into your ribs.stay there no need to go any lower. Going lower puts a lot of stress on the shoulder.
YOGA SEQUENCE TO WHEEL POSE: This sequence is targeted to those who feel strong but not open enough to do wheel pose, results may not be instant but these things take time & dedication. Do warm up well, I have a "Back Bending Warm Up" sequence in my feed,