I try not to worry too much about deadlines. If it's done, they get a finished item. If it's not done, they get it on the needles along with the pattern so they can see the finished item. Then I just take it back and give it to them again when it's finished.
If I'm trying to get it finished so it can be worn/used at an actual event, well then it just won't be worn/used. I rarely create these types of deadlines for myself.
No worries, no stress!