You should get great views of Jupiter, Mars and Saturn now with your scope: just remember to let it cool to ambient temperature for a while: if you take it straight outside and start observing it will take a while for it to cool, and you might find that the views aren't as good as later on when it has settled down. Also, let them get higher in the sky for the best views, and don't try to go too high power at first- often the sky conditions will dictate that a lower power gives the clearest views. For example, last night there was a fair bit of upper turbulence from my place, and 150x was about the limit of sharp viewing. This was easily enough to see the Cassini division on Saturn, lots of cloud detail on Jupiter, and a fair bit of detail, including what looked like clouds on Mars.
I second Rigel003:
anytime is a good time for Saturn and Jupiter (except when they are behind the sun!
), but now and over the next couple of months is particularly good for Mars.
Don't wait for June 3- get out there tonight!
Happy viewing,
Dean