Writing 1,667 words generally takes 60-90 minutes depending upon how fast you type. If you are hand-writing, it may take even longer, but not much.
Do you need to sit down and write for the full 90 minutes?
Consider splitting up your writing session times into two or more sessions throughout the day. Thirty minutes three times a day still gets the job done if you prepare yourself well.
NaNoWriMo fan and author, Ysenia Vargas offers the following advice:
Basically, for every hour of the day, from the time you wake up until the time you go to bed, you are responsible for writing 500 words an hour. After writing 500 words for that hour, you can do whatever you want until the next hour begins.