Sounds like a bit of air in the system or something.
Every day when I first turn it on I get water for 3 seconds, then nothing for 30-40 seconds, before it carries on.
Doesn't do it the rest of the day, unless I've really chucked the van about at lunchtime, then it may do it on the first afternoon window.
I'm used to it now.
I turn the tap on first, then pull the hose out, extend pole etc...by then the water is starting.