Help with low dose aspirin

At my 9 week ultrasound, my doctor told me to take low dose aspirin when I hit 12 weeks because with hypothyroidism, I’m more prone to develop preeclampsia. I just hit my 12 weeks and I don’t know if he meant to take one dose which is 4-8 tablets or to just take one tablet. I don’t see my doctor till 11/19 so I was hoping a mom could help me.