Objective: The identification of predictors of psychosis remission could guide early clinical decision-making for treatment of first-episode schizophrenia (FES). Methods: We analyzed two non-independent subsamples of patients with FES ages 18–40 years from the OPTiMiSE study dataset to investigate the demographic and clinical factors that might help to differentiate “late” remitters (i.e., not in remission at week 2 or 4, but achieving remission within a 10-week follow-up period) from non-remitters within the same period. Results: Subsample 1 included 216 individuals (55 females, mean age 25.9 years) treated with amisulpride in an open-label design who were not in remission at week 2. Early symptomatic response between baseline and week 2 (odds ratio (OR) = 4.186, 95% confidence interval (CI) = 2.082–8.416, p < 0.001) and older age (OR = 1.081, 95% CI = 1.026–1.138, p = 0.003) were the only variables significantly associated with a higher probability of psychosis remission at week 4. Subsample 2 was composed of the 72 participants (19 females, mean age 25.1 years) who were not in remission at week 4 and completed a 6-week double-blind randomized trial comparing continuation of amisulpride with switch to olanzapine. Depression at baseline (as measured with the Calgary Depression Scale for Schizophrenia) was significantly associated with a nearly 3-fold lower likelihood of psychosis remission during the 10-week follow-up (hazard ratio = 2.865, 95% CI = 1.187–6.916, p = 0.019). Conclusion: Our results reinforce the importance of assessing depressive symptoms in people with FES and support the relevance of an early response (as early as 2 weeks) as a predictor of clinical outcome in this population. Clinical trials registration: ClinicalTrials.gov identifier: NCT01248195, https://clinicaltrials.gov/ct2/show/NCT01248195.