soon, so on

Soon or soon ( one word ) means after a short span of time, or in the near future--
Will the train arrive soon?
Don't eat a snack now; we'll be having dinner soon.

So on or so on ( two words ) means continuing in the same way or fashion, or for this reason--
Put one bolt in like this, and then another, and so on until there is a bolt in each hole.
Mark the fiirst one "A", the second one "B", and so on until they are all marked.
The speaker talked about the budget, the financial situation, and so on.
The seats are all filled, so on with the show.

Now that you know that, you can say--
"The election will be held soon, so on with the voter registration drive!"

Note--not to be confused with "sew on" ( rhymes with so on ) , meaning to use a needle and thread ( sew ) to attach ( on ) something--
Do you know how to sew on a button?