Q: Can I use the Telescope to look at the top of the discard pile any time during my turn to decide whether I want to use a card that lets me draw more?

…like Space Jackpot, or Draw 2 & Use ‘Em, or Draw 3 Play 2?

A: Yes, you can use it once, at any time during your turn. You could also use it to look at someone’s hand before deciding with whom, or whether to pay Trade Hands.