I have both difficulty stopping something (if it's not completed) and then starting something new. For example, I'm reading this forum, but I have an appointment and need to get ready to go out. I find it hard to draw myself away from tbe forum before I've finished reading it to go and get ready, which means that I'm late and have to rush at last minute to get ready and might be late for my appointment. Or I'm unaware of time, and suddenly realise I have only two minutes to prepare for a lesson.
I also find it hard to start tasks. If I finish one lesson with one student, I need a 5 minute transition phase before I start with the next one, because I need to mentally adjust to that student. Or if I need to cook at 3pm, I won't start until 3.30pm because I keep finding things to do or getting distracted, I'm kind of spacey and it take a huge effort initially to get myself focused and mentally on the task.