tl;dr: there's a 50/50 chance that one year within the next 5 will be more than 1.5°C over baseline. Currently, the record (2016) is 1.25°C.
That's not the same as the IPCC target, which would be a long-term average below 1.5°C above baseline. But reaching a single year at that level, so soon, would be a very strong indicator that we'll see many more years at or above that temperature.