attached the timetable for your reference. we took the 10am 忠孝敦南 (bus stop in front of Sunworld Dynasty hotel), arrived the park around 11:45am, and left the park at 8:35pm. My son is 5-yr old, he enjoyed the park very much.
we arrived the park around 12noon, spent 2.5 hrs in small world and doraamo and lunch, then went to water park at 2:30-5pm, honestly, the water park not big, but there are 3 slides which my son loves so much. Afterwards, my son played the (machine games), weather is good and no need to queue up, the children spent 2hrs there, there was firework at 8:10pm but we did not watch it because we need to catch 8:35pm bus, otherwise next one would be 9:25pm. we did not take dinner there.