Hard to say. Age can impact fertility, and so can weight. So it's a question of how much more time you want to take before you start TTC.
I was, hmm, 100 pounds overweight when I got pregnant with my first. I have PCOS (mild version, thank God), which negatively impacts weight & fertility both, so even though I was trying to get pregnant I was pretty surprised when I did!
Statistically speaking, overweight women have higher incidences of gestational diabetes & preeclampsia (and first-time moms also have higher incidences of preeclampsia). I had problems only with preeclampsia with my first, and there are things you can do once pregnant to help ward that off, like the
Brewer Diet. (Note: that's a way of eating during pregnancy,
not a weight-loss method.)
Your number one priority if you are overweight and pregnant is, IMO, to find a doctor or a midwife who will not ride you about your weight. Sometimes overweight women gain weight while pregnant, sometimes they do not. The truth is, your baby will take from your body what it needs, and you will get what is leftover. About the last thing you need to be obsessing over while pregnant is if you're gaining "right." I have seen otherwise intelligent and confident women turned into little puddles of goo over this question. And I hate it.
Some overweight (or even previously overweight) women have serious mental issues with gaining weight during pregnancy, or with even just their tummies getting bigger. IMO, that's something for you to consider when you're thinking about trying to conceive. Pregnancy is a very stressful time to begin with (and our modern medical establishment is good at exacerbating that).
There is some evidence that being overweight leads to higher incidences of interventions like c-sections, but my gut feeling is that finding a good professional to take care of you during pregnancy is the best way to help head off a section. (The section rate in the US is around 30%, compared to 10% or 15% in much of the rest of the world.) There is
no evidence that being overweight leads to bigger babies, and I haven't heard of any suggestion that it affects nursing potential either. Though you will play **** finding maternity clothes in the stores. The fashion industry doesn't like to think of us fat girls having sex, much less getting preggers.