The 19th + 20th picks combined can probably allow us to move up to like 12th overall.
My guess is that you're looking at being able to move up 2-4 spots, based on past draft day trades.
Usually, the trade is because you are in love with a specific player who you think is going to be taken by the team drafting 17th or 18th, so you try to leap-frog them by finding a team just ahead that doesn't feel strongly about any player who won't be available before the 20th pick rolls around.