A good epoxy coat turns your garage from a cave into an actual extension of the house where nothing sticks to the floor and spills just wipe right up. The whole process usually takes a few days from acid-washing and patching cracks to letting the final topcoat dry hard. You want to schedule this during warm, dry late spring weeks so the humidity stays low and the chemicals cure right without bubbling up.
You are looking at about $2300 for a professional job, but prices swing wildly depending on who you call. Get at least three local quotes to see who is actually diamond-grinding the concrete instead of just acid-washing it, since prep work is the only thing keeping that floor from peeling up in two years.
That 18-month window is a hard deadline, not free money, so if you still owe anything when it ends, standard interest rates will kick in on whatever is left.