Don’t stress too much - it’s not that hard to put your oven construction project on the back burner for a while.
No matter the stage of construction, simply cover the oven with a heavy duty tarp and place HEAVY OBJECTS (like cinderblock) on each corner of the tarp. Keep the tarp tight to prevent it from blowing around during high winds. Plastic Tarps and Masonry are mortal enemies during high-winds (masonry always wins).
Once you are ready to get started again, simply remove the tarp and inspect the oven for any damage. You may need to soak the old firebrick if a long period of time has passed.
Remember - dry firebricks absorb moisture from mortar like a sponge!