How much time does it take for synapse to strengthen?

[Fenix117]

I know that there is short term synaptic plasticity which lasts to few minutes and long term plasticity which lasts longer, but I still don't understand exactly how it works. Does synaptic connections strengthen from minute to minute as we learn, or does it need a longer time, like hours, overnight sleep, days? Or is it like with muscles, they will be stronger after they'll regenerate and grow over days.