The honest fact is that the earlier you can send a new couple your gift, the better.
It is more interesting opening gifts while the wedding glow and rush are still present.
But do not put yourself under any kind of pressure. If you are not financially or emotionally up to the task of getting a gift during the wedding, rest easy.
You have up to one year after the wedding to send in your gifts. Do it at your own convenience and who knows? It may be a pleasant surprise to the couple.