Applying for indefinite leave to remain in uk ( permanent residence )?

i have employment not requiring a work permit visa .in this visa i need to live here 5 year .i will complete 5 year in june 2009. but please tell me .i go to my home country every year for three months. i have spent 450 days out of uk .i have valid visa until 2010 . shall i apply in june 2009.how many days can i go out of uk in five years .please ......thanks