<b><i>Background:</i></b> Although the experience of reception of borderline personality disorder (BPD) diagnosis was previously researched, the process of mental adjustment to this diagnosis remains both empirically and theoretically unexplored. Theoretical concepts describing the structure of lived time in borderline patients, which underlies adjustment to diagnosis, living with the diagnosis, and recovery from the disorder, namely, immediacy and instantaneity are not empirically verified. <b><i>Aim:</i></b> This study aimed to phenomenologically describe the process of mental adjustment to the diagnosis of BPD and to uncover its underlying temporal structure. <b><i>Methods:</i></b> Semi-structured phenomenological interviews based on Giorgi’s descriptive phenomenological psychological method and Cottle’s Circles Test. The participants were 10 white, adult women diagnosed with BPD aged 20–32 years. <b><i>Results:</i></b> The process of adjustment to BPD diagnosis comprises three following stages: (1) a cumulative feeling of inadequacy preceding the diagnosis, (2) the outburst of diagnosis, (3) a battle of Self fragments while adjusting to the diagnosis. Simultaneously, the diagnosis modifies the relationship between the self and illness in a way that previously scattered problematic issues become inscribed into the self as symptoms. At the same time, these symptoms are relatively separated from its “healthy” part. The temporal structure underlying this process is discontinuous. Particular temporal dimensions are distanced from one another, and the inner images of the past and present consist of unconnected, emotional peaks. The present resembles waking up from the lethargy of the past, while the future consists of two colliding scenarios – either being free of or in control of symptoms. <b><i>Conclusion:</i></b> Clinicians should pay more attention to the pathway of identification with BPD diagnosis and its underlying temporality. This is crucial for recovery and may allow adjusting therapeutic interventions to the patients’ needs. Treatment should aim to enhance the patients’ abilities to reflect upon their temporal experience to merge their fragmented narrative identity and better situate them in the recovery process.