The date or time of the commission of the offense need not be alleged in the indictment, unless the date or time is essential to the offense.
If the date or time is not essential to the offense, an indictment shall not be held insufficient if it does not state the proper date or time, or if it states the offense to have been committed on a day subsequent to the finding of the indictment, or on an impossible day.
All allegations of the indictment and bill of particulars shall be considered as referring to the same date or time, unless otherwise stated.