SB is such a bugged class that we will need multiple iterations of patches to get to a good level. I would guess 8 weeks of PTR with weakly updates would be enough, but this will never happen.
When we get some of the biggest bugs patched midseason or a bit earlier, the best SB players will test the SB in season 6, more bugs and balance changes can then be tested on the PTR and Season 7 will have a playable SB class.
If nothing happens midseason, the bug fixes and balance changes will be chaotic as usual and we will either end with an underperforming SB in Season 7 or a still overpowered one.
And the overpower damage multiplier from max life need to be adjusted as well. Another Season with just overpower-builds will be too frustrating for most players.