Activity and completion

One useful aspect pair

читати is imperfective: reading as an activity, habit or process. прочитати is perfective: reading something through. A prefix is not a universal recipe; learn aspect pairs individually.

Explicit perfective forms

Past: прочитав, прочитала, прочитало, прочитали. Future: я прочитаю, ти прочитаєш, він/вона прочитає, ми прочитаємо, ви прочитаєте, вони прочитають. These non-past perfective forms refer to future completion, not a present activity.

Choose meaning, not a time-word trick

Compare Вона читала текст (she was reading/read the text as an activity) and Вона прочитала текст (she read the text through). The same day can contain either kind of action.

Завтра я прочитаю текст.