An attack across the strait with a large buildup of troops (150,000+) and SEAD campaign will need months of logistical preparations which comes with the risk of giving the ROC enough warning to build a nuclear deterrent.
However, a rushed attack with less than three months of preparations is likely to be repulsed by the ROC military unless China resorts to a Grozny-style leveling campaign that would unfortunately make the whole endeavor unprofitable.