You do not have to feel confused. All these four formats are almost the same which means "it is almost the time ...../ It is going to .....soon" I give you an example: 快下雨了 就下雨了 快要下雨了 就要下雨了 All these means "it is going to rain soon."

快。。。了 就。。。了 快要。。。了 就要。。。了 ------------ 快到了 就到了 快要到了 就要到了 They all means " we are going to arrive"

they are used to express the action in the future 快。。。了 = soon 就。。。了= immediately, afterwards 要 just adds certainty

两个意思一样，不过表示的时间不一样。快……了 是很快，但是还要等一会later，可能是几分钟。就……了 是now现在，马上，下一秒将发生的事。就比快时间短

actually,no difference in Chinese,mean ( be going to ) in english