Two. As others said for comparison. If you only have one and it starts to seem to start getting weaker, you have a tendency to think, well, its time of year, lack of nectar, etc. Denial that something could be wrong until its too late. If you have two, queens being equal, they should rise and fall together. Yeah, I agree to forget about splits the first year. You need more knowledge than bees the first year.
Don't count on luck and swarms unless they are common around you.