You seem to be referring to an ischemic stroke. Yes time does matter, if you were treated in a center where thrombolysis is performed it has shown to be effective in the first 4.5 hours, ideally under 3 hours (from the onset of symptoms). What thrombolysis means is injecting a drug which dissolves the clot formed in the vessel before the brain tissue is irreparably injured from the lack of blood flow. It depends where you live though. In my country due to costs and lack of proper organization it s not performed at all till now (hopefully it ll start soon). Also in more wealthy countries it still isn t performed everywhere, so it s a question of having access to the appropriate center in that short window of time. There s also the option of thrombectomy (entering with a catheter in the vessel and remove the clot) but that s an invasive procedure performed in even fewer centers. While these interventions could have improved the prognosis I don t want to make things look too simple. These procedures just augment your chances for a better outcome, but there is no guarantee and sometimes can have hemorrhagic complications which could aggravate your condition. The best means of avoiding stroke consequences is by preventing it which means lower high blood pressure, treat diabetes, stop smoking, treat high blood lipids, healthy diet and lifestyle. These are the interventions shown to be of more benefit than thrombolysis or any other treatment.