Plan a realistic time line for the various stages.
Are there any deadlines that are fixed. For example, it is
useful to have a draft completed prior to presenting the data at scientific meetings. Then
finish the paper off when you get back based on feed back you have received.
Work backwards from these fixed deadlines.
Make sure you leave enough time for several revisions. A
dozen or more revisions is not out of the question.
Make sure you leave time for a fewmore experiments
and a little more analysis.