I doubt it if anyone is going to suggest you to make your own dates but do the best job of remembering them as best as you can. Home Office is sometimes lenient if they are convinced that your main interest is to live in UK and absence was out of your control.

You can also explain this in your cover letter when you apply. How long have you been in the country? They do have a rule of 450 days but there are exceptions also.  I also suggest that you also talk to solicitor or use Citizen Advisory Bureau.  They provide you free advice and in large cities they also have Law centre that will provide you free advice on immigration issues. On Television also they have some programs that will advice you but they charge arm & leg (900 numbers).  I watch 817 on sky but never called them. There are other televisions station that provide this service on 900 numbers and usually charge around 50p/minute. I dont like these services but listening to them will not cost you anything.  That's what I do.