Hi Monikah - once the charity have all their incoming donations totalled 'til year ending 31 March 2010 they can send out the receipts.  I'm not too sure how long that process will take, but WV seem to be pretty efficient.  I've always rung and asked for the receipt - I'm not sure if they send them automatically.  Their 0800 number is good for that. 

You can get the charitable rebate form off the IRD website if you have a printer.  I was surprised at how easy the whole process was.  (Don't forget to apply for the childcare rebate on the same form, if that applies to you! ).

I co-ordinate a World Vision donations group at work consisting of about 20 people's donations.  I apply for the charitable rebate on everyone's behalf.  It went sooo easy when I recently applied for the rebate for 1 Apr 08 - 31 Mar 09 tax year. 

World Vision sent me the receipt within a week.  I filled in the appropriate IRD form and found the money in my bank account within the week even before the tax summary arrived in the post!

If you need any other advice in this area just PM me - I'm quite familiar with it, or just go to www.ird.govt.nz and there's a section in there on charitable rebates with lots of helpful stuff.