By grace period, you mean during the 6 months since you have graduated (or stopped attending school) and the loans are still deferred for a short time before first payment is due. Right?
Nothing negative will happen per se. You will have paid your loans off satisfactorily. Fully paid loan accounts will remain on your credit reports for many years (10 tops.) The major plus is no more interest on the loans.
That being said, you should not see a drastic score jump simply because you have paid off your loans in full so quickly. I believe the positive accounts will be weighed the same if they are paid in full immediately or paid as agreed monthly.
Personally I would stretch out payments for a short time at least to show creditors a sustained positive payment history while at the same time pushing out that 10 year drop off date. Student loans tend to help with AAoA since people have many of them for very long times. I would especially not pay them all off at once if I only had enough cash on hand to pay the loans with no substantial buffer left afterwards. I would rather have a huge rainy day fund over paid off loan accounts.
Youcanalwaysdiverselyinvestthemoneytooffsetsomeoftheinterestontheloans. Putitinamoneymarketaccountand slowly payyourloansofffromthat. MaybeinvestafewgrandinCDs, fewgrandinT-bills, T-notesandT-bonds, etc.
