Something major is on the horizon for you. You have a wedding or a shower or a major party marking a major accomplishment. Perhaps it's a business meeting that involves speakers and venues and agendas and timing. The date is set. Invitations were sent out weeks ago. You are making arrangements for food and drink and other festivities. A band has engraved your date on their calendar.
As the day comes close, however, a tragedy or perhaps illness occurs and you are finding yourself compromised. Do you forge ahead with the celebration? Do you follow through with all the plans even at the probability that you either can't attend or the person of honor might not be able to arrive?
Everyone who is on your guest list, although looking forward to your event, will not be comfortable knowing that you decided to did not delay the celebration for their sake. People are flexible. The celebration is about the guests of honor first and foremost and if they can't be there, the guests will understand. They won't want to be there either.
So when you make the decision to cancel a social and/or special occasion, it's simply a matter of making a few calls. Guests will understand. The quickest way is a mass email. You can also solicit the help of a few trusty volunteers. If you have RSVPs then let them know that the occasion has been cancelled. If it's postponed, let them know this also. If this was a working event that required a deposit, make sure to take care of refunds as quickly as possible.
Call the vendors, caterers, etc. Talk to the venue and make sure any deposits you placed on it might be returned to you. Cancel any transportation, babysitters, let arrangers know that plans have changed. This way they can attempt to find other employment on that particular date.
If you have speakers or a band, make sure they know that plans have changed and they can book with others. Stay positive. Thank them for assisting you and wish them well. You don't have to tell them everything. Just let them know that you are sorry that the date has been cancelled.
Making the decision to cancel an event will make it easier to move forward. It won't take as long as the planning part. It will take less time to make the call and let them know that plans have changed.