I have done this in the past. Missing the start of the event is WAY BETTER than missing the middle or end. You know how when you are playing and there are 3 days here, and two days there when you have nothing to do? When you miss the beginning, you don't have that. You just start and play hard all the way through. Set timers, play during middle of the night potty breaks, etc. You have to be very careful not to send people on long tasks, right before you need them. The good news is that the steps will already posted here, reddit and/or the Wiki. You may have to judiciously use gems to speed through a task or Welcome a character, so that a long task can be run overnight. You may need to use gems to purchase the final items needed to get the last character Welcomed in time. But it can be done.
I completed most of the Wreck-It-Ralph event on my Windows game without being able to play for 8 days in the middle of it, when we went to Japan. "Most" because I failed to get Ariel's comfy costume, but I didn't care about that one.
I'm actually going to miss the start of this one. We leave for London on Saturday, so I won't be able to start this event until late Sunday (on my Windows game). Annoyed because I am going to miss a week of movie theater videos, and I need every gem I can get in order to get the 500 we'll need to welcome the two Premium characters. I'm already giving up having gems for the float and building. I am sitting on 340 currently.