First, allow me to get this rant out there: it really toasts my marshmallows that "Advent Calendars" always begin on December 1. They aren't Advent Calendars, then....they are December calendars.
Steve at A Song of November mentioned that he's apprehensive about putting up an Advent wreath with a 2-year-old in the house. I was going to post a comment, and maybe even bring him back to the Marauding Marsupial in the TTLB Ecosystem level but I realized that I needed more space for this. Sorry, Steve. So here goes:
Don't skip the Advent wreath just because you have young children. The Advent wreath has been great for our children during this season. Three times now, Big Daddy and I have been through the Tremendously Terrifying Twos at Advent wreath time and I'm pleased to announce that no one has been hurt yet. However, now that we have a Teenager in the house, I'm thinking it might be a good idea to keep a fire extinguisher at hand.
Maybe you have one of those cake plates that sits high off the table. Set your wreath on top of that, if you need to keep it away from the little one. Let your kids take turns blowing out the candles. We have two older children and they want to light the candles, so Little Brother gets to blow out the candles every day.
In our house, our preparation plans revolve around the Advent wreath. When Middle Sister was about the age of your younger son, she didn't understand why we didn't have our tree up at Halloween like the mall does. (OK, she still doesn't--but that was when she first expressed it). Until that time we had put our tree up toward the end of Advent, when we got to it. But she needed something concrete--so we started a family tradition of putting the tree up on Gaudete Sunday. We would tell her, "When Father lights the PINK candle at church, that's the day we put up our tree." We do a lot of decorating on Sundays, since the whole family can be together. It all ties in well with doing a little more preparing each time Father lights another candle.
So if you don't have a wreath up now, it's not too late to start. Go for it!