How long does it take for you to know whether or not you want something serious with someone?

I watched a video last night where this guy was saying that guys know what they want from a woman within the first 15 minutes of meeting them.
I don't remember the guy's name, so I can't find the video, but it was in response to a clip of a podcast where these girls were saying they think guys don't know whether or not they want a serious relationship with you until after about a month or two.

Guys, are either of these true for you? Does it just depend?
Within the first 15 minutes
Within the first month or two
It takes longer than a month or two
It just depends
Select gender and age to cast your vote:
How long does it take for you to know whether or not you want something serious with someone?
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