First fireworks season

Last night for the first time this year we had noticeable firework noise. We have a gorgeous three month old pup, Socks, for whom this was a new experience.
We turned the TV up a bit and tried to pretend it was perfectly normal to be in the middle of a World War and Socks was curious at first but seemed not too worried by it.
We didn't have a plan, should we have been getting her ready somehow? Have we left it too late?
Is it best to keep her inside after dark until this passes or might we convince her its normal if we take her out on a lead and just reassure her.
Be grateful for any hints as to how to make sure we have a bomb proof pup!
Marco, by email