Yes, you do not need to state your Major until 2nd or 3rd Year (In fact you can state it before your graduation if you really want to).
However, the thing is, you need to decide roughly what you wish to major/minor in, due to the fact that you may need to do some courses in your first year to satisfy Pre-requisite courses in 2nd or 3rd year, otherwise you might be left with a semester that's not 24 UOC in total.
Even I know double-degrees are confusing, a friend of mine elected to mainly do Commerce courses first and 2 Math courses in first year, then doing the other First-Year science courses in 2nd Year.