New here, and I also found this to be annoying clutter. Essentially I think you might want a SmartList with a query of
dueBefore:_date_
where you replace _date_ with some specific date

You can look here to see some of the appropriate syntax that can be used in your search query http://www.rememberthemilk.com/help/answers/search/advanced.rtm


Others might have more elegant solutions. Mine is as follows:
I created a SmartList that I call Due with the intention of only having items show up in this SmartList that have certain Due date characteristics. I then feed this particular SmartList to Google Calendar, where I don't want to have a lot of clutter. Even if I just look at the SmartList in RTM I don't want the clutter of distant due dated items (as well as some other items as well).

So my query for the SmartList is:
(NOT due:never AND NOT list:"3 Perhaps") AND dueBefore:6/15/2009

For my query, what it is doing follows:
The part in ()
The NOT due:never finds all items that have some Due Date assigned, but this chooses more "fish" than I really want. I have a List called "Perhaps" with things that are Maybe/Someday (to use David Allen's terminology from Getting Things Done). For some of the things on "Perhaps" I have put in due dates that help me understand that particular list better and makes sure that I do actually consider some of these things in this lifetime. Nonetheless, I do NOT want them on my SmartList called "Due". Therefore the 2nd part within the () is to exclude these items and is accomplished by the
AND NOT list:"3Perhaps"
Finally, the last part is the AND dueBefore:6/15/2009
It is this last part that for the SmartList will exclude items with distant DueDates.

In order for this to work for me, I have a recurring task that reminds me to change the date in my SmartList that I have filled in which is currently 6/15/2009 to some latter date and hence I am always seeing items about 30 days into the future.

Hope that was clear enough to be helpful to you. I recall reading that some have an approach to have items "snooze" so that they are only visible a short while before they are actually Due. I believe that approach is used by some to alert you that you might want to start on an item which has a DueDate in 7 days before it is actually due.

It is unfortunate, as many have pointed out that RTM does not have a Begin On Date field, nor as you suggest a way to hide items until a specified date. Lots of people here have found clever work-arounds for what seem to me to be significant short-comings in RTM.

Edward

You could use the weekly tip Using sleeper tags, found on the blog (April 2009).
Permanent link: http://blog.rememberthemilk.com/2009/04/tips-tricks-tuesday-using-sleeper-tags/

Plenty of people have posted about this. The key term is "start date". You can only work around it with a smart list.

I'll second rajjan's sleeper tags tip -- it's a very nice way of hiding tasks.

@lite1 : I have a smiliar smart list, but I use the dueWithin operator like this:

dueWithin:"1 week of today"

Could you use something like that instead of manually remembering to change the date? So in your case, could you use dueWithin:"4 weeks of today" and get the same result?