Your instincts are right. You could certainly repot this plant right now but waiting for a few weeks is a good idea. Where was this plant when you purchased it? What kind of lighting? They usually over fertilize plants for sale so don't mess with fertilizer right now.
The exposed roots are not a problem. Make sure you find plain potting soil, no fertilizer added and no water holding gimmicks such as sponges and gels. You want a pot only a few inches larger in diameter. I am guessing this is an 8 inch pot. Find a 10 to 12 inch pot clay I think is great and inexpensive, make sure it has a drainage hole, use only soil in that pot no rocks or gravel at the bottom above the drainage hole. Lightly compact. Keep the surface of the soil an inch below the rim for proper watering. You can cover the roots a bit. Firm the soil to get rid of air pockets.
Another thing to do is to raise the bottom of the pot off of the saucer about a quarter inch. Use pieces of flat tiles to do this or expensive 'pot feet' that can be fun...lions claws, eagle claws, bunnies...they make them in terra cotta to match clay pots.
Feel the heft of that plant in whatever pot it is in when it is watered well. Do not water until that heft becomes obviously lighter.
Balanced fertilizer, use half of recommended amount because of the low light situation. Osmocote works...14-14-14 or Dr. Earth's All Purpose 5-5-5. Use half of the recommended amount, okay? Wait to fertilize for a good month. Who knows what is in that soil right now?
Gorgeous plant. Do you have cats by any chance? Poisonous for dogs or cats or birds...'Dumb Cane' is one of its names for a reason. Dieffenbacia is very toxic to animals even kids. No kids or animals of your own? Just be aware when your friends bring their kids or doggies over to visit. Not that big of a deal as long as you are aware.