The best advice I can give a newlywed couple, don't wait to send your Thank You cards because if you do you'll never send them!! Scotty McCreery got married June 16th and he still hasn't sent out his Thank You's. Yes, he's been busy. He hit the road November 29th on his Seasons Change Tour but there's no excuse.
I'm personally a big stickler on Thank You's, and hand written ones at that. Everyone in life is busy and if someone takes the time out of their personal schedule to celebrate you and give you a gift... it's worth a few minutes of your time to let them know you're appreciative.
Now if we're talking etiquette, you technically have a year to get those Thank You's out (and a year to send the gift to someone that recentley got married) But from my personal experience... it's so much harder to make the time to send the Thank You's if you don't just immediately get it off your plate!
Congratulations Scotty McCreery!! Good luck on getting all those notes out!