When is the best time of day to test?

Hubby and I are ttcing for baby #2. I still nurse my son and my cycles range between 28-33 days. So I definitely need to track my ovulation so that I don't miss my chance. I usually test in the morning but I've heard the afternoon is better. I have a mild case of painful bladder syndrome and I drink a lot of water throughout the day to keep a flare up from happening. So I feel like my afternoon urine would be too diluted for an opk. Please help.

Here is a picture for reference