I applied for HSMP in Nov 07 and have a 2 years visa expiring in Dec 09 (With wife on dependant visa expiring same time). We are expecting our first baby around May 09

1. Apply for Baby's passport and then visa around May end or June in UK. And then apply again in couple of months for FLR
2. Apply for my FLR along with my wife and baby around June 2009 which will be 5 months in advance. Now am not sure if we can apply for an extension 5 months before?.
If I am able to apply in June 2009 and its for 3 years, will I get extension for 3 years starting June 2009-June 2012 or will it be Dec 2009-Dec 2012. Reason being, to apply for ILR i believe i should be in UK for a period of 4 years and 11 months which wont be satisfied if i happen to apply in advance for the above mentioned reasons.
This forum helped us a lot in preparing for our HSMP application when i applied first time and hope experienced members can guide me in this regard.
Really appreciate your inputs.
Many Thanks.