Waiting until January to start ttc

Okay, so I am planning on starting to Ttc in January. I got pregnant with my first son the first week we tried. And I have a feeling it will be the same way with our next baby. That's why am waiting till January to try and get pregnant. I want them to be at least 2 1/2 years apart if not longer. It will also make it where I am my biggest in the fall so I won't be so hot. The thing is I am kind of afraid that it will take us longer to get pregnant then I am thinking it will. I'm getting the itch to start trying early but I also really want to wait. Has anyone ever had trouble conceiving their second child?