I have 2 Gen. Admission tickets, with ticket nos.on each, and they are marked "Guest Entry" with a no. above. Marked "Good for One Timed Entry Any Day". Can I go any time, or do I need to wait until date when timed entry tix become available.

Call the information desk at the museum and get the correct answer

You're going to have to use it for that reserved time on the ticket

I think that you have to go on the day and time that was chosen

The whole point of choosing a time and date is to control the flow of visitors. Use the pass as prescribed.

You have to choose what time you will arrive and what time you will leave on the same day