The time required by expatriates to become proficient in their new positions is important to both employers and employees. The existing literature on expatriate success is largely blind to what may be significant factors in the process of creating and sustaining job performance amongst the expatriate group: the effect of time and the effect of home country culture. In this study, we examined the impact of five organizational antecedents (role clarity, role discretion, supervisory support, coworkers support and perceived organizational culture dissimilarity) on corporate expatriates' Time to Proficiency (TTP) in four home country cultures (HCC) samples. We specifically examine the direct impact of HCC on expatriates’ TTP and the moderating effects of HCC on TTP’s organizational antecedents. We used a self-administrated questionnaire on a sample of 224 expatriated managers in New Delhi, India, from four different home countries: France, Germany, Korea, and Scandinavia. To analyze the data, we used PLS Graph version 3.00, a component based Structural Equation Modeling technique. We tested the impact of HCC on TTP by examining the mean scores in TTP across HCC. Differences between path coefficients across the four HCC were analysed using path coefficients’ comparison. Our results show that 1) on the full sample, all five organizational antecedents have a significant impact on expatriates’ TTP, 2) TTP mean scores significantly vary across HCC and 3) the organizational antecedents of expatriate TTP and their relative importance vary across HCC. Our results are broadly consistent with the cultural studies: except for the Korean expatriates, the larger the cultural distance, the longer the TTP. Knowledge that HCC is a significant predictor of TTP suggests that organizations may need to reconsider their international staffing policies, especially in the fields of recruitment, staffing policies and support policies.