The average timeline between S-1 filing and offering pricing is roughly one month. However, the exact time of offering announcement is unknown and depends on how soon the company will receive the form EFFECT from the SEC, which depends on how complex the company's financial disclosures are. Usually foreign companies such as Chinese companies will take longer in receiving form EFFECT.
The offering pricing press release can be announced as soon as the company receives form EFFECT, but since we cannot publicly see the EFFECT until one day later, it can theoretically be announced anytime. See the SEC filing cheat sheet for more details.