Returning to running advice

I was running 5k a couple of times a week with an average pace of 5.30-5.40 per km in 2017. Then we bought our own house, had our first baby and I started a new job. It’s now 2 years on and I’ve tried a few times to get back into then jogging to work off my dad belly but not sure how to go about it.

Im skinny with a bit of chest and belly fat but would like to work this off and build some definition. My question is should I start from scratch using the couch to 5k app as I did many many years ago or should I just try to run 5k and stop if i feel too tired. I did 3k on friday my calves are aching and my ankle is a little sore. My pace was 5.36 per km.