do the method of slow oxygenation. Before you sleep the night before, uncork your bottle, and just let it sit in a cool ventilated place. That night i just turned on the air conditioning (i usually don't) and just put the open bottle on my table in my room as i slept. I recorked it about 2pm but i feel you can leave it uncorked until you have to go for dinner.
don't need to decant it, just pour out the wine in the glasses and enjoy a long dinner and enjoy how the wine evolves further in the glass.
also for your own personal enrichment, i would suggest trying the wine at various stages. So when you just opened the bottle before you go to sleep, pour out just a little, swirl it a bit, take a sniff and sip it down. Do the same thing the next morning when you wake up and then when you actually drink it with you gf, you can make the comparisons at different stages. Keep in mind u just have to pour out a bit, enough for one or two sips, just to get a feel of the wine.
sometimes i don't fully recommend an extended decant, unless it really is a very young and tight wine and you want to drink it as soon as possible. i find the slow oxygenation tends to let the wine open more naturally and becomes more expressive. there is no hard science to back this up, just my experience and other wine enthusiasts'.
i once brought a 2002 white wine from a good american producer to work, uncorked it and let it sit in my office the whole day before recorking it and bringing it to dinner. It was very expressive and lovely. The downside is that it is very time consuming and u need to do your research to see if the wine is meant to be drunk very quickly or something that you have to let breathe for a while.
regarding temperature, if you are going to keep for 3 years or more, i would really recommend you invest in a proper storage conditions.