There is no point in spending all that time on your plan if you do not use it to keep yourself on track!
Your plan is unlikely to be absolutely right first time and it is perfectly acceptable to make changes! You should use it to monitor your progress so that you can take action when problems occur.
You must make notes about your progress and changes you make to your plan. Keep a record that will be clear to the moderator - you could use comment boxes, a project log, a column in a table, etc.