The standar to charge a Lipo batt. is one capacity, the charger instructions will be of big help on this, since you are using kero start it may run down your batt. after 3 to 4 starts if you like you could recharge between flights or get another batt.
Try not to drain your Lipo all the way down, half way is good this way you know that you have enough for the nex flight and no cycling just charge and go but as you did with your NiCads keep and eye on them for the firsts 3 to 6 flights to make sure there are in good order.

I'm not the best on batts. or Lipos but so far in all my years of using batts of any kind I never had a problem that I coudn't fix regarding my batts or a crash, maintanace and inspections I say has kept me flying.