How long and how often should I water my concrete?
Best is to keep it damp "forever." Design strength for most concrete is based  on 28 days at 21C/70F. The early part of the cure is the most critical. Time is doubled at 50F/10C and reduced at higher temperatures - so long as it's kept damp.

Covering with damp cloths/burlap/sacking and then covering that with plastic can help to keep it damp longer (from a single application of water.) Just covering with plastic helps some. How frequently you need to apply water will vary with climate and how much you have done to keep the water in place.