Please help me check the two sentences. Which one is correct in grammar.

" But lately I've started keeping a small study diary. I write down all I need to do and when it needs to be done by. "
Is the sentence above correct in grammar?

Should I change it into :
" But lately I've started keeping a small study diary. I write down all I need to do and when they need to be done by. " ?

Thank you , I am looking forward to seeing an answer! Haha😄😄😄

Question

Please help me check the two sentences. Which one is correct in grammar.

"  But lately I've started keeping a small study diary. I write down   all  I need to do and when it needs to be done by. "
 Is the sentence above  correct in grammar?

Should I  change it  into :
"  But lately I've started keeping a small study diary. I write down all I need to do and when they need to be done by. " ?

Thank you , I am looking forward to seeing an answer!  Haha😄😄😄

Answer

But lately I've started keeping a small study diary. I write down all I need to do and when it needs to be done".

*this sentence is correct, you don’t need BY at the end

Answer

Actually there is no much difference between the two sentences, but if i were you i would prefer the second sentence because of this word  ' all ' 👋

Answer

They both makes sense!