PCT applications are typically published after the expiration of 18 months from the priorty date of that application (see:
http://www.wipo.int/pct/en/texts/articles/a21.htm#_21).
Thus, if a PCT application has been filed (and not withdrawn prior to publication) with a priority date of April XX, 2011, it will likely be published on:
1. October XX, 2011, if that day is a Thursday and not a official holiday for WIPO;
2. the following Thursday, if October XX is not a Thursday and the following Thursday is not an official holiday;
3. the next date indicated by the International Bureau, if October XX is not a Thursday and the following Thursday is an official holiday.