Approved green card need advise to entry in united states

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I was entered in Usa jan 2005 worked on H1b to till jan 2009. while iam working in Usa my employer has filled Gc for future employment.i left united states feb 2009 and working with same employer in india.i got approved my Green card on june 2010 and it was mailed to my frieds house. now green card is in my hand. my question is can i use my gc to enter unitred states. because it was approved 7 moths back while iam in india. first time entry on gc what is the time frame to enter in usa. like in 6 months or 1 year. plz advise me.

thanx in adavnce