Normally, I commit about 20% of my time to working on a project. However, we are behind schedule, so I am planning a "coding vacation" in a few weeks, where I will sequester myself in a hotel room, and work about 12 hours per day for 5 days straight on only this project.
How can I enter this now in FogBugs, so that the Completion Date (Probability Distribution) report will account for this upcoming marathon coding session?
The challenge is that EBS is attempting to gauge future results by past performance, which obviously doesn't include you moving from 8 hours per week to 60 hours per week on this project. It wasn't really designed with this use case in mind.
The best you can probably do is to look at the Burn Down chart and figure the impact of this event on the 95% probability line. When you look at the chart, you'll see how many hours are left to obtain the 95% probability of releasing on time; you also know how many hours you will have added to that by a certain date (the end of your "vacation").
We'd be very interested to hear how this works for you and where your final release date ends up. The most important part of Evidence-Based Scheduling is the "Scheduling;" that is, knowing how to apply your time/people resources to accomplish a goal (meet a release date). If this works or fails, it will speak to the accuracy of the Burn-Down chart and its usefulness.
While I'm not particularly familiar with the inner workings of EBS, one thing you might be able to do if you want to see how that schedule change (going from 20% on the project to 150%), you could adjust your schedule to be 12 hour days, and set your time to 100% on the late project. My guess is that EBS takes your current schedule and time allocation into account when it does it's forecasting, so you should see a corresponding shift in the predictions because you are telling it that you are now pouring a much larger amount of time into that project.
Just remember to set the time back once you are done with the session/predicting.