Method Would cold enough water cause unconsciousness before the actual drowning part sets in?

[prelapsarian]

Currently in the middle of a huge snowstorm. The lakes are frozen but given the warm weather immediately before this I could probably bust the ice open. That got me thinking, how fast would hypothermia set in and knock a person out if they were to dive in with no protection to the elements?

Eyeing drowning as my most viable method since my hanging plan fell apart (door too flimsy, nowhere else to suspend myself from), which sounds miserable, BUT easy to do since I don't know how to swim. Just dive in and it's already too late when my SI inevitably kicks in and I try to chicken out. I would ideally like a way to be unconscious or incapacitated while the actual "my lungs are full of water and I cannot breathe" part is happening. Don't have access to any tranquilizing substances...