If you decided to have cocktail hour in between your ceremony and reception, please always have enough food for your guests. It doesn't matter if you decided to have just a station or tray pass too, just choose the food accordingly to your theme or what do you think your family and friends will like best.
Every wedding is different but usually the cocktail hour is set up between the ceremony and reception to allow the couple and the bridal party to take pictures as well as the closes family members. Some couples depending on their cultural believe and traditions have the cocktail time as the guests arrive so they can have their first view or take pictures with the bridal party before the ceremony time.
If you are having a Bar, decide if you will like to have a signature drink, cash bar, hostess bar, just hostess for a while (usually two hours) then cash bar or hosted bar making a deposit depending of your possibilities or continue paying as your guests are consuming (usually finalize by the end of the night).