If baby is on bm, water is not necessary. In any case, best to give bits of water after each meal just to rinse babies mouth and get baby used to the taste and texture of water. With that said 6months is a good gauge.
Your due date is Jan 17. Water to your baby as in? Your unborn baby? or Borned baby? Or baby that was born this year?
My lo didn't drink water till she turned 8 months old as she didn't eat much solid and was on Breastmilk only.
Jorelle Aw