[whpalmer4]

I think it's a fool's game to try to set your due dates to anything but when they are due. If you set it early because you know you also have something else due that day, then you have to adjust it again when someone tosses something else on your plate (and for completeness, if someone removes something from your plate, but that seems to be mostly a theoretical possibility!) Having said that, I do like to set my default due time for new tasks to be somewhat before the end of the day, just so there's some breathing room in case the person I need to talk with likes to leave early, etc.

The piece that is conspicuous by its absence in this discussion is the review. OmniFocus has a wonderful review tool for helping you methodically monitor the individual progress of all of your projects, and it is how I deal with the problem you mention. As I look over my projects while doing the reviews, I make note of which tasks need to move forward in the next few days, and if they do not have a start date or due date to cause them to appear in the Forecast view, I flag them. My workflow is basically to bring up the Forecast view and complete everything I can that is due today (or overdue), then work tasks from the flagged list and the starting today list. For tasks that I've assigned start dates to because I want to do them on that day, I'll bump the start date to the following day if I haven't completed it by the end of the day so that it continues to appear on the Forecast view.

To deal with the specific example you gave, I would put a start date on the "Give the list to Bob" task for the earliest time I could expect to do it on Monday, and I'd probably flag it as well. If there was some chance I would see Bob before Monday, I might not put the start date on until such time as that possibility had passed, just so that if I ran into Bob, I could pull up my Agenda:Bob context and see the action there ready to go, instead of having it hidden by a future start date. If it takes any appreciable time to give the report to Bob, I'll put an appointment in my calendar for perhaps 8:30-9:00 AM to give Bob the report so I've got the time blocked out to deliver it.

OmniFocus does an excellent job of remembering what you told it about your obligations, but the scheduling of the work to meet them is up to you. IMO, the review is the key to making sure the right things are getting your attention so that you can successfully meet those obligations. There's quite a bit of material on the forums about various review approaches.