Thanks to all of you who answered my question, the reason why i'm asking is my FLR's issue date and expiration date is different.
Based on what you know/think when are you supposed to apply ILR?
I thought that i should/could apply ILR 28 days before the expiration of my FLR. But i have learned that i can only apply ILR 28 days before the end of 2nd year of my FLR issue date.