[msadowski]

I think it's worth experimenting quite a bit to try to see what time works for you to exercise. For me early morning works best as there are no unplanned meetings etc. and I can easily do it 3 times a week.

Also as someone mentioned already in the comments C25K programme might be a good start for running as it mixes walking and running until you build up strength and stamina to run 5k.

Good luck!