Aphasia due to stroke affects communication and quality of life. Most stroke survivors with aphasia receive speech and language therapy. Although an early start of treatment is advocated in clinical practice, evidence for "The earlier, the better" in aphasia rehabilitation is weak. Hence, clinicians are faced with the dilemma of when to initiate intensive treatment: as early as possible, when most of the spontaneous recovery occurs but when patients are often ill, or later, when the patients' condition is more stabilized. Here we discuss whether aphasia outcome is affected by timing of treatment in relation to stroke onset and whether there is evidence for an optimal window of time during which language therapy should be provided. Findings from various rehabilitation research fields are discussed and combined to provide principles for future research.