“时机”偏重机会。我们一般说，你一定要抓住时机，去完成某件事。 ”时机“means chance, we can say,you must take the chance to do something. “时间点”是某一时刻，例如：在这个时间点，我们通常都在上课。 "时间点"is a certain time. e.g. At this time, usually we have class.

The phrase "时间点" is not a proper usage in Chinese. If we refer to a certain moment (a certain point of time), we can use "刻" or "時候" e.g. at this moment = 在這刻 = 在這時候 "时机" means chance. e.g. You have to grasp this chance = 你要抓緊這個時機

Generally, both can be used at the same time.

剛好在這個時間點上. 也可以說. 剛好在這個節骨眼上.