As an occupational therapist, it is extrememly important to get as much tummy time in as possible. It strengthens the core muscles needed to learn the basics of rolling, sitting, lifting head, and also increases upper body strength. It reduces the risk of having a flat head in the back and wearing a helmet. It also reduces the risk of damage to the hip joints from being on their back too much and reduces risk of spinal issues later in life as tummy time is what helps the curves of the spine form in the neck and crawling will for the curve in the lumbar region.
Positions to try: tummy down across legs, laying on chest (but not as effective if you are sitting up), prop upper body up on boppy pillow and bottom in the hole of it, laying on a wedge, and the famous foot ball hold in your arm.
I hope this helps. I started TT with both my boys when we got home from hospital and both of them can tolerate an hour of awake time on tummies at 1 month. They both started rolling when they were 1 month also. HTH