There is the variant that the JGA planned as a surprise and the bride or groom is simply picked up at home on a given day. Of course, this can also be difficult to lose and always comes with a certain residual risk. In most cases it makes sense to record at least a period, about a week, with the person to be celebrated.
The same applies to the group of participants. If the person organizing the JGA is part of a regular circle of friends who often do things together, you don’t have to think twice about who should be there. In all other cases, it might be better to either ask directly who should be at the JGA, or find out by asking one or the other specific question.
At the last point, however, the bride and groom are finally out The friends always finance the evening together. As an organizer, therefore, try to know a little in advance which budget is in order for the participants. In this context, you then have a free hand to organize an unforgettable bachelor party in Hamburg for all of you.