Can I paint my floor in two stages with epoxy?
Do an experiment on a slab of anything of similar roughness -- a chunk of garage floor would do.  
Make a virtue out of a necessity:


Make the edge at a logical division of the space, and change colours of paint, or change colours of glitter at the transition. If you want to be fancy, make it a zig-zag or Peano curve
Mask shapes onto the floor.  Stack the stuff on the shapes.  Move stuff back, Do rest of floor.
Apply the glitter as a secondary cover mixed with a clear coat.  Apply it with a stencil in blocks. The pattern of glitter distracts from the seam.
Instead of left/right, move everything to the edge, measure the maximum distance from the edge of the room.  Mark a rectangle with that distance from all the walls.  Do the centre.  Now move everything into the centre and do the edge.  Can be really cool if you change colours of paint.  (Buy one additional colour, and mix it into all the remaining paint.  So if you did the center in light green, buying a can of dark blue would make the remaining paint dark green-blue.  Yellow + blue grey = brown.  



If you want to have more fun, use a stencil, and lay down patterns of the edge colour as a second coat on the centre area.