When to say, 'He/She is the one for me?'

I can't honestly say as I am still just in a relationship. I mean being in a relationship doesn't guarantee that it's for keeps, right? But based on my opinion, I think you'll know that he/she is the ONE if you can envision the rest of your life with him/her. If you've seen the best and the worst but you're still able to accept and love your partner unconditionally, fully, without inhibitions and wholeheartedly. If you know that you can't see yourself with anybody else but him/her then I guess that's it.

i think there is no time when you think the other one is the one for you, you will learn lots of things about some one and when the time comes you will get shock that what ever you concluded was totally opposite of what you were thinking so no one can judge the other perfectly. yes if you get married instead of judging you has to maintain your self how your partner likes it, that is the couple which leads in better way
gohar

that is something that cannot be measured you just know the time is right when your heart tells you it is time. It is different for different people