What do you think its the best time for the bride & groom to arrive at their reception?

Your mama is mistaken. Both the host and hostess, and the guests of honour, should be present to greet the guests when the guests arrive. You can take pictures at the park on another day, or in the morning before the wedding if you aren't superstitious, but you cannot with good grace "shelve" your guests for an hour or two while you go off to do your own thing. The host -- whether that is you or your parents -- must make arrangements for food and drink in a way that will satisfy their guests' tastes, within reason. I wouldn't serve beer with a meal because my guests would prefer wine or sparkling water; but you seem to be saying that *your* guests would appreciate beer with their food. In that case, you would be a gracious host to serve beer with the meal.

this is being very hard on the guests. Why all that picture taking on the day of the wedding? can you not get it done before the wedding. I think you need to be at the reception when it starts. I think you should arrange for the bar to be open when the guests arrive. I think the reception should immediately follow the ceremony.

Here is a reception timeline http://wedding.theknot.com/wedding-planning/wedding-reception-planning/articles/a-traditional-wedding-reception-timeline.aspx Bride and groom should arrive after the cocktail hour . . . which gives them about one hour for photos with their photographer. Keeping your guests waiting for longer than an hour . . . well, some would frown upon it. Unless there is some unspeakable emergency, anything longer than one and one-half hours is just plain rude. Waiting until 6:15? That is totally unacceptable. I urge you to do some rescheduling. Please show mama the reception timeline above.

As I recall, my wedding is similar to yours because we had a church ceremony, park pictures, and reception right afterward. My suggestion is this...since you have the whole morning free, why not request to take the park photographs at 11am-12pm? It only takes an hour to take those photos coz I had mine taken for less than an hour. After that you guys can head to the church ceremony. After the church ceremony you can have all the time to take group or family photos at church. Once done, you can head home to relax for at least an hour or two. OR you can take the park photos right after church and be done by 4:30pm. You should be at the reception at 5:30 to 6pm. Its nice to have dinner around 6:30pm-7pm so that your guests won't starve to death. Its common courtesy for the bride and groom to be at the reception area before the guests show up. Its nice to take picture with the guests as they come in the restaurant and give those pictures to them as party favors. Normally the bartender should show up at the restaurant half an hour before dinner is served. Its weird for the bartender to show up late and the guests have nothing to drink. If dinner is served at 6:30pm then you can have the first dance 7 or 7:30pm. Don't forget you have to cut the cake before the dance...or it depends on your tradition. Don't make the guests wait until 7pm to get their cocktails..that would be weird. This is a long email...hope it makes some sense :) Good Luck. You need to priority your schedule and run it thru with your family before finalizing anything :)

I would have the ceremony, do pictures while the guests mingle, find their way to the reception venue and mingle some more (maybe have a couple of drinks and some snacks before dinner). Then arrive when pictures are done, in time to greet the guests and sit down to eat dinner. You could have beer and wine before the bartender gets there. Some people like to drink a glass with dinner. Then just have the bar open when people start to dance and party. I wouldn't move the time because then that is about 3 or so hours of time between the ceremony and the dinner (assuming the ceremony ends at 2pm). The times you have now, it would be 2 hours between the two venues and that is enough.

On time. * * *

The bride and groom arrive after the ceremony to greet their guests. Allow time for picture taking maybe you can schedule some time with your photographer before the wedding.