First of all I recommend making a practice cake now, just cook, ice and cover with fondant. Just to see how long it takes you.
You can bake your cakes a week or two in advance and store in the freezer, wrap well in plastic and foil. You can make your BC a few days early too. When your ready to start working on your cake (let's say three days in advance) pull cakes out of the freezer and let sit on the counter to thaw a bit, don't unwrap so the condensation forms on the foil. I like to torte/level my cakes partially frozen, makes it easier to cut. Use a long serrated knife (or leveler) to cut off any domes so your cakes are not flat (place a clean cardboard circle over cakes and put a level on top to make sure they are level
Each cake should be at least 4" high (some go taller but 4" is standard) either torte your cakes (cut in halves or three layers-depends on how much frosting to cake you want) or use two layers (which would mean you'd need to have baked 4), start stacking. Underneath each cake you'll want a cardboard round or piece of foam core-cake circle, dab of icing (to make cake sit on board), filling (buttercream or whatever you'd like), another cake layer, etc. Since your new to this I highly recommend using a crumb coat of BC-this is a very thin layer of BC it holds the crumbs in your first layer of icing. This is where I let my cakes settle, you can do it overnight (just let the cake sit this avoids budging) but if your in a hurry place a large tile over the cake (something with enough pressure to
Push the cake down without crushing it).
Next day (2 days before party) apply a thicker layer of BC to your cake, smooth out any bumps-any imperfection will show under your fondant, let it setup and cover with fondant.
Day before party finish adding decorations to fondant covered cakes. Are you just going to let the handles lay on the side of the can? For the paint cans I mean.
This is just a fake time table, you can split these steps up even more if you need to. The fondant painter pallets can be made as soon as you want. I'd make a template or find a picture othe computer, copy and paste into a word document, resize and print on card stock. You can also cover both sides with clear tape then cut out the design, this way you have a faux laminated template. Roll out fondant, place template on fondant and cut out with clean, new exacto knife, repeat. Let dry on cookie sheet covered in wax paper then add colored icing or fondant, just store them in a cool, dry place (make sure it's out of direct sunlight which makes fondant fade).
I hope this helps and makes sense to you. Good luck!