How to express the idea of "I will have" or "they will have"? Use the futuro anteriore or future perfect tense. Here is what it looks like:
  Alle sette avremo già mangiato. (By seven we'll already have eaten.)
  Noi avremo parlato al padre di Anna. (We will already have spoken to Anna's father.)
  The futuro anteriore is a compound tense formed with the regular future-tense form of the auxiliary verb avere or essere and the past participle of the acting verb. The table below contains the full conjugation forms of verbs in futuro anteriore.