This is truly a once in a lifetime event. More accurately a once in many lifetimes event. Jupiter and Saturn will be extremely close together. As in view them both in one eyepiece or a pair of binoculars close together.
Without visual aid they will look like a single very bright star – some are calling this the “Christmas star”.
And it is interesting this will also be the Winter Solstice for 2020. Every day is longer from this point forward until the middle of summer.
Looking west/soutwest 45 minutes after sunset 
This is where I’ll be on Monday evening December 21.