Sometimes life gets in the way. You have great plans, high expectations, and set some completion goals that that are doable but require maximum attention if they are going to be achieved. Then something happens! An emergency trip to support or help a family member, you get ill or have unexpected company. Someone calls and wants to visit for a couple of days, you want to see them but this will set your plans back. Use the interruption as a break and modify your expectations. As long as you get back to your project there is no harm done. Think of it as a temporary time out. Any number of things can get in the way of your goals and break the flow of your work. The best thing you can do is schedule your delays. This means to expect some interruptions and start your project well in advance of the completion date.
Scheduling your delays does not help with the break in the creative process but it takes some of the pressure off from a time perspective. It also means when you are making the completion goals mentioned above, tone down the expectations. If you have no interruptions and the project is complete with time to spare then take a break, clean up or get ready for, or start the the next project. Sometimes when you have been dealing with interruptions and you return to work you have a new perspective. Subconsciously you may have dealt with some design issue and a problem, or direction to proceed has been resolved. Sometimes an interruption that diverts your focus can be a good thing and returning to a project can be looked forward to.