That's fine for a cycle using mature media (your ceramic and foam from the pond filter).
Your ammonia eaters seem to be there in large numbers hence the drop form 3 ppm to zero in 4 days. However you don't appear to have many nitrite eaters - I wonder if that's due to the temp as a pond would be running cooler than a tank, though I don't know how temp could affect them.
1 ppm ammonia is converted into 2.7 ppm nitrite, so the first 3ppm that you added is now around 8ppm nitrite which is off the top of the tester scale. And the second 3 pm ammonia means you now have around 16 ppm nitrite in there. This is at danger level as the nitrite eaters stop multiplying around 15 ppm nitrite.
Have you tested your tap water nitrate yourself? Nitrate testers are the least accurate of the ones we use so it is better to use them to compare levels. Try testing nitrate on your tap water and tank water at the same time so you can compare the colours side by side. If the tank colour is higher than the tap colour, you do have some nitrite eaters.
And if you are using liquid testers, are you shaking one of the bottles even more than the instructions say to?
Once you've done these nitrate tests you'll know for sure if your nitrate is going up and if it is you do have some nitrite eaters, you just need to grow more.
You have just completed stage 6 in the method stickied in this section. Because you are potentially at the upper safe limit for nitrite, don't add any more ammonia yet. Go from stage 7. Since your ammonia is dropping very quickly, you'll test in 2 days and get zero ammonia, then test again in 4 days to get the second zero ammonia. That's when to add the 1 ppm dose. Then repeat this until your nitrite falls below 1.0 ppm
Please don't be tempted to add more ammonia more often than this or your nitrite will get high enough to stall the cycle.
It shouldn't take very much longer