I will file provisional patent, then publish it. Can I file PCT application after that based on US provisional priority date?
If yes, what is the maximum time I can have before filing PCT application? Is that 12 months or more?
Yes you can. You must file the PCT claiming priority to the US provisional's filing date within 12 months from the day you file the provisional. The same is true if you also want to file a US non-provisional application (i.e., one that will be examined) based on the provisional.