About relationship

It's pretty hard to understand, what you mean without further information or mind reading.

In general, yes, timing matters, because if you wait too long, all the relationship members will be dead.

If your question is about the timing to start a relationship, it matters and you can get an idea of the timing when you get to know the person.
Usually, you don't go from stranger to girlfriend or boyfriend in 1 day. So you take your time, talk to each other, get to know each others situation and if you notice, the person would liketo have a partner, it may be the right timing to make a move.
You should not go to a stranger and ask "Would you like to have a relationship with me?". That would be bad timing.

I would also call it bad timing, if he/she broke up with someone recently. Just take your time, get to know each other, be there for each other and maybe there will be a relationship one day.