If your currently working on more than one project take a couple of minutes to read Jeff Atwoord’s post on multi-tasking. He concludes with:
I've often pushed back on demands to work on multiple projects at the same time. It can be difficult to say no, because software developers are notoriously prone to the occupational hazard of optimism.
We typically overestimate how much we'll actually get done, and multi-tasking exaggerates our own internal biases even more. Whenever possible, avoid interruptions and avoid working on more than one project at the same time. If it's unavoidable, be brutally honest with yourself-- and your stakeholders-- about how much you can actually get done under multi-tasking conditions. It's probably less than you think.</blockquote>