Are you a surrender noob? It is okay, I have seen one hundred plus.
First and foremost, you can surrender at 17 minutes in 3s. Don't worry about the minimum surrender time for 5s because if you find yourself waiting for that you are the biggest noob and will probably get your nexus destroyed soon anyway.
When you have good crittance on your team, don't surrender - crittance is an investment in the mid and end game. Once that infinity edge is poppin and the enemies are getting their tails crit, you may witness a large swing in momentum. That's the only strat you need to worry about now, because if you ain't crittin, you ain't shit.
No critters? Surrender.