Which one is correct "they didn't" or "they don't" when using "for" afterwards [closed]
Solution 1:
Didn't, i.e. did not is in past tense and does not agree with the rest of the sentence and therefore, you would need to tweak the second half for it to properly fit:
Makki and Mattsun didn't have time to execute their plan, for two not-so-soon-expected guests suddenly made an outstanding entrance!
However, since the event is ongoing, you may want to replace "didn't" with "don't" instead:
Makki and Mattsun don't have time to execute their plan, for two not-so-soon-expected guests are suddenly (or currently) making an outstanding entrance!