Trying not to conceive!

Quick question. Been on Safaryl for 1 1/2 month now. My husband comes home from deployment in a few days, really would like to NOT use condoms, but not totally trusting the birth control yet... Only the second BC I've been on, I was on Lo LoEstrin for 1 month, had bad side effects, switched to Safaryl. So far so good. Never used BC before now, always just pulled out. Been sexually active for a little over 4 years now, Never been on any bc until almost 3 months ago & pretty much never use condoms... Wondering if anyone has any advice about how long I should be on this pill before totally trusting it without a backup birth control. Thanks :)