Fig. 1 You have sixty minutes.
I also have one, three and thirty minute timers. I use sixty when I simple MUST get a few hundred words down on the page. I use one minute as a kickstart that can see me happily working away two or three hours later.
This is for some fiction writing. I know that the most crucial thing is to sit down and get on with it. Without distractions. I don't allow myself distractions during this hour. My usual way of doing things is summed up in two words 'anything but ...' Typically I will prepare, research, think about it, jot down some notes ... even sleep on it, even, in fact, especially in the middle of the day.
I've got four or five hours in the bag. I need to lay down a couple more today.