How to communicate order of events

Our wedding will be at two locations: a church ceremony followed by a cocktail hour and reception about 7 minutes away. We will have 230 guests, which is the maximum limit our reception venue allows. We aren't doing a "Catholic gap" with hours of time between them; Once the ceremony concludes, people are free to make their way to the reception venue, where cocktail hour with appetizers will be available for them (but they don't have to rush of course, they can take their time if they don't want to go right away).

The problem is that we are anticipating a number (my fiance says 50) of uninvited guests for the ceremony, because they will hear through word-of-mouth when the ceremony is and want to come. This doesn't really bother me, I think it's a compliment that people would want to come see the ceremony and wish us well. It also doesn't cost us anything for uninvited people to come sit in the church pews. We have friends who got married at the same church and had this happen: they had quite a few people they hadn't seen in years show up to the ceremony unexpected (they also had a reception at a different location).

The problem is that we can't hand out programs at the ceremony with the full order of events on them, because the uninvited people would see when and where the reception is, and that seems rude/improper. But we also want to be sure we very clearly communicate the location and time of the reception to all invited guests. Of course the info will be on the invitations, but with two locations we want to be sure we communicate very well.

Besides having the information of the reception and the general timeline on our website, my fiance was thinking we could put it on the back of the invitations too. This is a bit unorthodox, but I think it's better to over-communicate for invited people who might be elderly and won't navigate the website.

We were also thinking of having the reception-only order of events printed at the tables at the reception, so all reception guests can still see when the grand entrance, dances, speeches, cake cutting will be. I know an order of events for the reception isn't mandatory, but as I guest I've appreciated having a sense of what will be happening when.

Thoughts?