Do you expect instant decrease in price of good and services as dollar loses value to naira? No, this can't be possible. It will take some times before this can become effective. Remember alot of product has been produced down with an expensive materials by campany, wholesalers have also store goods at high price. Most will want to sell part or all of this before selling at new price. I believe if naira continue to appreciate like this, it will definitely has effect on goods very soon.
Do not think naira just increase in price, the government also manipulated it by decreasing its price and later increased it. The price of phones, laptops and electronics have fallen 50% already but local products are not decreasing in price while some increased. If there should be deflation, it also supposed to be on all products, be it imported or produced locally. If other prices have decreased, those that bought at high prices by selling at low prices will also not lose.