Howto avoid receiving old events in FSEventStream callback (FSEvents framework on macOS)

Question

i'm having trouble with the macOS framework FSEvents: when i call FSEventStreamCreate and pass kFSEventStreamEventIdSinceNow for the "since" argument, i still receive kFSEventStreamEventFlagItemCreated events for files that have already been generated a few seconds before the stream has been created and scheduled.

NSArray* paths = createDummyFilesOnFileSystem();
sleepForFiveSeconds();

CFRunLoopRef runLoop = ...;
FSEventStreamContext context = ...;
CFTimeInterval latency = 0.5;
FSEventStreamCreateFlags streamCreateFlags =
   kFSEventStreamCreateFlagUseCFTypes |
   kFSEventStreamCreateFlagNoDefer |
   kFSEventStreamCreateFlagWatchRoot |
   kFSEventStreamCreateFlagFileEvents;
FSEventStreamRef stream = FSEventStreamCreate(NULL,
   &fsEventCallback,
   &context,
   (__bridge CFArrayRef) paths,
   kFSEventStreamEventIdSinceNow,
   latency,
   streamCreateFlags);
FSEventStreamScheduleWithRunLoop(stream, runLoop, kCFRunLoopDefaultMode);
FSEventStreamStart(stream);

Is there anything i can do to avoid receiving kFSEventStreamEventFlagItemCreated notifications for those files created earlier, or any way i can filter those out ( e.g. by looking at other flags)? I've already tried flushing the stream initially and passing FSEventsGetCurrentEventId() for the since parameter, but that did not help either.

Thanks!