it totally depends on the child - i think average is 3 days but a week is totally normal for some - they can really have huge leaps in weigt, height, mental development, physical development etc and it all comes in a short period so they need the extra fuel (helps put it in perspective...)
it might take a few days and all goes back to normal or it could take longer to get back to sleeping as before GS...i have experienced a bit of both with 2 kids x many GS :lol: 3 months was the biggie for both of mine - 6 mo Olivia only had 1 nightwaking and then just ate more solids in the daytime and drank a ton of formula

then 9 mo was a biggie again