An SSB consists of 4 OFDM symbols (TS 38.211, Sec 7.4.3)  and a CORESET (Sec 7.3.2.2) can span 1-3 OFDM symbols dependent on the configuration. So, the complete “package” can be received very quickly in 7 OFDM symbols.  The OFDM symbol length depends on the configuration but for 15 kHz subcarrier spacing it sums up to ~0.5 ms.