Can I create recurring volunteer opportunities that may have different dates and times for future occurrences or dates and times may TBD?
It is somewhat possible.
You can create a recurring volunteer opportunity where you choose the time and the day of the week for the most frequent occurrence. Then you can edit each individual occurrence to change its time. When you edit it, you can also choose whether it applies to all future occurrences.
On the TBD's, perhaps not. What would parents be signing up for if they weren't clear on the time?
You may still use the above instructions, but include a note that all dates after a particular one are TBD and may be adjusted. If someone signs up for a recurring volunteer opportunity that is subsequently edited, i.e. the time has changed, they will be notified of that change.
There are a couple caveats. First, a volunteer opportunity cannot be moved more than 24 hours. This means that you can't change the date of the occurrence.
You may also consider creating a recurring opportunity for just the dates/times you know. Then you can create another one, or extend the until date of the first one, to generate new opportunities once those later dates/times firm up.