It is some years now since I filled out a DLA for my daughter (quadraplegic CP, epilepsy, reflux etc) however, as part of my job now, I don't deal with SN childrens, but older carers and I always tell them the same.
Think of all the hardest aspects of your role - be it, toilet training, nights, meds, social... and then paint that picture into 24 hours timescale that they are asking about.
I'm saddened to have to still be saying this but you have to paint the toughest picture, wht worst case scenario if you want a successful DLA application.
If your attitude is "actually, its not so bad, or I manage that ok" they recipient will think "that's fine and move on". Well it might have been fine when you wrote it, but 2 days later when you've been up all night and the same problem re-occurs - you won't be feeling fine about it at all. You will be tired, sad and feel isolated and whether you need the support on the day you complete the form or not, you sure as well might in a couple of weeks.
So in summary:
Write worst case scenario, think of every little thing you do in 24 hours, how many times you have to change your child, clear up because of your child, get up in the night....
Only then will DLA sit up and treat your application with the respect that it deserves.
Hope this helps.x