If you take a 2 gallon bucket of pool water, then every 1/4 teaspoon of 6% bleach is 10 ppm FC and you can see how much it takes before the chlorine starts to hold. If you had CYA loss over the winter from bacterial conversion of it to ammonia, then for every 10 ppm CYA it can take 24-30 ppm FC so if you lost 50 ppm CYA then that's up to 150 ppm FC to clear it. Hopefully, you're close to the end, but a bucket test wil be a faster way to find out.

You could also get an inexpensive ammonia test kit from a fish/pet/aquarium store but you might have gone through much of the ammonia by now. Do you measure Combined Chlorine (CC) even though your Free Chlorine (FC) goes to 0 after some hours?