Currently the first ever RPC timeout is only override in Callables.retrying when retries are disabled: https://github.com/googleapis/sdk-platform-java/blob/main/gax-java/gax/src/main/java/com/google/api/gax/rpc/Callables.java#L103. If someone only configured a total timeout and it's smaller than the default initialRpcTimeout, their first ever RPC won't respect the overall deadline, which could cause the operation takes longer than desired.