So here's the thing. Our ceremony venue and reception venue are roughly a half-block from each other. They're within walking distance. We want to give plenty of time for us to take pictures and I kind of screwed up on the invitations. Our ceremony is at 3:30, we're expecting to be done around 3:45-3:50. On the invitations, I put the reception would begin at approximately 5:00, which only gives us an hour to do all our photos (we aren't doing a first look). I was wanting to push our entrance back to 5:30, but I don't want to have an hour and a half gap for people to wander around aimlessly.
I know most people fill this with a cocktail hour ... first off, our venue doesn't allow alcohol (city-owned), and second off, we don't have the budget to fill this time in with extra drinks or food. Would it be appropriate to just open the reception hall to guests at 4:30 (or maybe earlier), have music playing, and maybe have a light snack available like popcorn or cotton candy (which would fit our amusement park theme)? And then we show up at 5:30 for our grand entrance. Or would that be too long of a gap without a real filler?
I'm really overly concerned about leaving a huge gap for people to get bored in because of a wedding I went to in April (that broke pretty much every etiquette rule there is) where there was a 3 hour gap between ceremony and reception so that the bridal party could go bar hopping and get drunk before the reception.

I don't want to come across as rude and abandoning our guests, but I want time for photos!
And yes, I realize 5 days out is kind of last minute to be thinking about this but I was trying to finalize our timeline and panicked.