This varies substantially. Some get it, some don't.
Also, in the dark or in low light, the pupils dilate to naturally adjust. But in bright light, such as the sun, they naturally constrict and become smaller because of its sensitivity. Mydriasis and miosis, respectively.
I'd guess to say that in your case, with speed, you are looking at around half a day if what you meant is you are taking 7 lines total with one hour breaks in between. If it's too much of a concern, the only way is to simply not dose that much and that often.
Some people are more sensitive, so if you are one of those, then you could say you are on a prescription medication which can easily have that effect as well.
Edit: This time frame includes those 7 hours as well. But yeah, it's just a guess and you could try timing it yourself so that you know next time. Everyone is different so that's probably the only sure way you would know in your own, personal case. Good luck.