Actually not in all cases there is an "Update base currency" in between, but also not in all cases, when it is present, there is also a delay.
Here is an example without delay:
2018-06-07 15:59:51.099 [IB] INFO [JTS-EServerSocket-73] - [2019957:104:104:1:0:0:0:INFO] Placing orderId - 4...