If a woman wants kids and the man wants to take his time, how long can we wait for him?

Obviously at my age (15 and in HS), I'm not one bit ready for kids and not dating yet. However once I become an adult and get into a relationship where we both want kids in the future, how long would be too much waiting.

I know men don't like women to be nagging and other women adviced us to wait for him, give him time but we what if he's ready in a decade or till he's in his late 30's (assuming he's within our similar age range) but what if we don't want to be that old or past our time by then? We don't have that advantage of waiting a decade for him. On average, how long can a woman wait for him before it gets worrying?

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All women and men keep advicing us to be patient, let him take him time and not rush him... ok but when is it too much time? At some time, he has to be ready or else that goes against our years, against our fertility and our ability to produce healthy kids.
If a woman wants kids and the man wants to take his time, how long can we wait for him?
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