as Arkenophas said:
Korg needs to visit Bareshade
Bernard needs to visit you home, then
you might need to massage Korg like several times (i went all length to where i continue)
the massage option will be available around 2100hrs... same time the hotspring owner told you it is usually free..
Ah ok i see.
Its actually once a day you can massage korg, no specific time.
But when i massaged him, then chose "Can i continue?", and then "Continue with the massage" thats when my character suggested that he visits the hotspring, and then the conversation option showed up.
I did give him multiple massages before so idk how many times is needed for that option to show up.
i dont think the (many massages you need to give Korg has anything to do with him going to the hot springs)..
but the things needs to be done are...
1. attempt to massage him
2. mention that he really needs a massage at hotsprings
3. visit bareshade with him (during the way with him back and forth, there are some options - they might be related
4. bernard visiting your house
5. maybe the tailor - i'm not really sure if thats a must- the tailer to visit you
some of the above objectives can relate to the version of game you are playing ..
good luck my friend, try to explore other places in the game..