Glad your pharmacy will do 3 day advance..

Golden rule of Lamictal more than 3 days off you have to start over from day one 25-50 mg and titrate up as you did when first put on it, due to risk of SJS ( Stevens Johnson Syndrome)

You will be fine with them offering 3 day advance.. Are all your meds set for auto refill.? My Walmart offers that, My insurance allows for refills 3 days in advance, Ask to have yours to set auto refills, That way if there is something with no refills they can send fax to your Doctor before you even run out.