Wow! A new born and you’re thinking about working out already. Good for you. There’s no universal ‘best’ program but why don’t you try this:

4 - 6 thirty(ish) minute sessions (per week) of varied activities. No workout the same in the one week. Variety is great for your body and your mind. Here are some suggested activities to incorporate:

Stair walking / running, weight training, boxing, stretching, swimming, soft-sand walking, jogging, bike riding, skipping (maybe wait a while), any of the fitness classes and whatever fitness machine floats your boat -  stepper, rower, strider, grinder, etc.

As long as your limbs are moving, your heart rate is elevated, the intensity is appropriate (not too hard), you’re sweating a little and you’re consistent with your sessions, you’ll see some results.

Good luck

Craig Harper