It may seem like a non-entity, but the time that you try on and buy shoe matters. This is because our bodies go through several changes throughout the day, thanks to the blood flow difference.
If you buy your shoes early in the morning, you may find that they fit well then, but they never really fit like that the rest of the day, and you will end up being uncomfortable.
The best time to go shoe shopping is later on in the day because you fit the shoes when they are most likely to be swollen, which means that they will fit well at all times of the day.