Can we feed formulated milk like nan pro 1 every 4 hours to a 1 month old baby...is there any harm in feeding formulated milk?

No harm with formula: feeding for a 3 months old, if you aren't able to fully breast feed, unless the baby is allergic to the formula, he/she can get it until age 2 years without any supplement, you can also feed your baby whenever he/she needs, no need for a strict schedule, babies after sometime will time themselves for a feed every 3 - 4 hours, make sure you your baby gets enough, good luck