Advice needed

Hi everyone

i have applied for citizenship in july 2008 and on march 2009 my case has been transferred to my residential province , now due to the fact my spouse who is also waiting for her landing papers in her home country is about to deliver our first baby i have to go to see her in may 2009 , what should i have to do either inform right now the citizenship canada about my absence from Canada or wait for the citizenship test call letter and inform then only . Will informing earlier would be beneficial or is mandatory to do ?

Thanks in advance for your valuable suggestions