i find that with most conny roofs, gutter emptying and gutter cleaning jobs that the custy wants them doing between april and september because they spend more time outside and can see how nice they all look.
However i try to convince them that the best time for emptying gutters is straight after the leaves have stopped falling (soon) . The cleaning can be done any time of year because nobodies gutters have ever overflowed because the outsides of them are dirty.
Hope this helps