Originally Posted by Zenithale

... Just a noob question, can participate to a Dream Fest during the 30 min or you absolutely need to be present at the first second of the Entry Time? I ask that because after a lot of changes of Entry Times I was able to get a Dream fest at 00:00, then when that was the finally time (after few hours of waiting), I came few seconds after the beginning and the Participate button stayed grey...

Most likely your production has chosen a different Dream Fest time if your Participate button stayed grey. Only time you can enter if your Participate button turned pink. You can check the time selected by your production by going to Production page, located on menu button, and reading pink banner located below the "Top" tab. You can also look at time remaining for next Dream Fest by looking at pink banner located in Dream Fest.