Follow the stored esp value in the stack and then the next stored esp value until you land on the first return address, as shown in the following screenshot:
Figure 13: The last return address in the stack window in OllyDbg
Now, follow the return address on the disassembled section in the CPU window, as follows:
Figure 14: Following the last return address in OllyDbg
Now, you have reached the first call in the unpacked section, and the only step left is reaching the OEP.