Hard to say. We already see some intel 10mn cpu's but majority is "Delayed Broken 10nm Into 2019". They might appear anytime from >>November.
If you have something to play/work on and its not crying for help, then wait. All tech maps say if intel will make 9'th gen on 10'nm, we can expect +25% for sure. If not then 9'th gen will be just refresh, and no reason to wait.
Ryzen is great value if you have a little time to tinker. For anything except gaming AMD wins. If you have time, consider it also.