A scale would certainly make it a lot easier to work out how far your players are having to travel between points of interest

I mainly use Campaign Cartographer 3 Plus, but I also use GIMP as well - using them both together to make hybrid maps at the moment, but I'm only a novice with GIMP just yet, having only just figured out layer masks and paths

Maybe it would help to work out how big your planet is (Earth is 40,000 km in circumference, and many fantasy worlds are smaller than that), and then think about how much of the planet's surface this continent covers - how far it extends north to south, and east to west, then roughly work out from that how long and wide it is. That should give you at least an approximate scale to work with.