Your first time can take up to a week or better because your body has to use all the carbs in your body before it starts using ketones. Stay the course, and you’ll see results. Lots of water will help the process too.
Also, I’m not sure if you’ve read about the urine strips or not, but most of us that have been on the diet more than a month don’t use them anymore. Keto is a lifestyle/eating habit change more than a quick diet. The strips are great to start out “peeing purple” to know when you are in ketosis, but don’t live and die by them. For example, when I was usually peeing in the solid 4.0 range for ketones, but after working out (roughly 1.5 hours of cardio/weight training), the sticks would only show a small slight trace (I’ll save the science part of why lol). So yeah, the sticks depend on a lot of factors.