The most common “fault” grounds include adultery, desertion, cruelty and constructive desertion. If those grounds have met, you can file for divorce without any waiting period.
Absent a “fault” ground, you must wait one year after living “separate and apart” before you can even file for divorce. Under certain circumstances, the separation can include a period of in-home separation. However, that in-home separation must meet certain criteria and standard of proof. A special circumstances exists if you have no children, and if you have a signed settlement agreement which resolves all issues of your divorce (i.e. property and support). In that case, you can file after living “separate and apart” for only six months.