Remember to include the written accent on the i, as in í, for both the nós(we) and vós(you) forms of the conditional simple. This accent also tells you which part of the verb is pronounced with more emphasis. So make sure that you not only write the accent on the í, but also pronounce it more clearly!
Chegaríamos na hora marcada, se o trem não atrasasse.
We would arrive on time if the train was not late.