Good point. With telescopes, no, not in near future. But with spacecraft, it looks like any time after 2007- communication with any spacecraft won't be blocked by the Sun [after 2007 there will be large block of time, in which it never goes behind the Sun- well over 10 ten years. Considering the fact that at moment there is no planned mission and spacecraft could be launched earier- using long travel time (but extremely low delta-v [Swag that it would be less than needed to get a bird to GEO]). Which all means a spacecraft could be launched as soon as say 2005- doing that would mean you would need to start this project right now. In other words there is no reason to wait, as soon as you could develop a orbitor/lander, you could launch it.
To study with telescope, you would need to wait until about same time as launch window for manned mission (see my other post below:
http://www.habitablezone.com/space/messages/22279.html ).