@ClaireSmith has it right. If the Scouts are having a really good time, they will push to get to the meeting on time. <Warning: Old Fogy Scouter Tale> Back when I was an OA chapter advisor, the chapter leaders passed a rule under my suggestion: Start the meeting on time. First meeting, the room was empty and the opening, plus the start of activity sharing, was done to an empty room. Then Scouts started filtering in. The late attenders asked what they missed, but the Chief said to be on time next time and find out. (We let them know after the meeting). At subsequent meetings, more and more showed on time.
Yes, sometimes parents can’t get their Scouts there on time, but that still doesn’t mean the meeting should backup so latecomers can be filled in. That can happen later when they talk to their patrol leader.
Interest can be increased by the SPL and PL’s getting the word out about great things that are going to happen at the meeting/event.