I would lean toward using what you already have unless you have specific worries about it. Has it worked fine for you so far?
I have another vial arriving today. The next 8 mg shot is scheduled for tomorrow. My new sterile water supply arrives only on Saturday along with a filtering kit I have never used. Should I go ahead with the water I already have and take the full dose on the usual day, or hold off until the new supply shows up and accept being a few days late?