If you ever know of a time when your
allergies would bother you a great deal (
like if you were going to have to
do a major spring-cleaning, or doing a lot of dusting,...etc.), I would take one at least an hour beforehand. The meds work better taken in advance rather than taking them after the symptoms start.
Your cough is worrisome as it sounds like it could possibly be asthma. I thought I knew what asthma was (chest tightness, wheezing, etc.