Don't know what to do?

Hi! Everyone. I currently accept job offer to PNG-Port Morsby as Account Executive yet currently employed here in the Philippines. Don't know what to do? The agency gave me note that they will advice me when i can submit my resignation letter but our HR (current company) is a friend of mine. He want me to file my resignation this month so he can find my replacement soon.I asked agency to give me advice how long it take for processing of my Visa. they said it will take 1 1/2 months to 3 months.  I discussed to them that my current employer want me to file know, so i can teach the new one-they just said- your company need to find someone if that's the case because sometimes the visa come unexpectedly. maybe earlier than your expectation of 3 months.
I'm afraid, if ever i rendered my resignation  now and it takes months before i can go to PNG. Guys! help me please. Help me to decide. Thank you.

The general rule of thumb is NEVER to resign unless you have the visa in your hand.  You should not have shared this information without getting the visa, with your friend.  What he is saying to you is also not appropriate as he is mixing a personal confidence with professional commitment. 

My advice would be NOT to resign or even indicate resignation until you have the visa.  Just tell your friend that you passed up on the job offer if he continues to pester you.   And in the future, keep such matters to yourself and don't disclose - the more you share, the tougher the situation you put yourself in.