Hello: There is no really a good reason to take the medication at 6 pm. As long as the medication is taken at the same time everyday. There should not be any problem. The duration of anticoagulation depends on the number of times you have the problem and the cause. If this is the first episode due to a reversible cause usually duration is 3 months. if this is the first episode and no cause was found duration can go from 6 to 12 months. in patients who the cause of pulmonary embolism was cancer, duration of anticoagulation is indefinitive. if this is the second time you have pulmonary embolism the duration of anticoagulation is for life. This medication work as a blood thinner , as such main side effect is bleeding. The medication have many interaction with medications. regarding the food, specially those rich in vitamin K can affect its effects.