Hi Sweetheart. I'm 38 and just gearing up for my second cycle of IVF (the first was earlier this year, and unsuccessful).
I also had all kinds of good intentions before round 1, and then utterly failed to do any of those things. I was awful, and ate cake all the time (and I'm not being hyperbolic there; I really mean it) while constantly telling myself that tomorrow I'd turn over a new leaf and sort myself out; and then eating more cake.
For that reason, I'm a bit cautious about the idea of postponing treatment to adopt a magically irreproachable lifestyle, because my worry is that it turns into a stick to beat yourself with. I, personally, just couldn't do it last time around. No amount of deciding to be 'good' could get me to do it. If I'd waited a couple of months, I'd just have eaten a couple of months' more cake!
This time around, I'm actually much more able to eat sensibly and have laid off the sugar and piled on the protein. But I think it's largely because it is my second time that I've been able to do that. I'm not intimidated by the process because I've done it before, so I can stop being such a sugar-fuelled stress-monster.
At the end of the day, IVF is a process that you can't control and that, sadly, usually has a larger chance of failure than success in any given cycle. So, I don't in any way blame the cake for my last cycle not working; and if this one doesn't work it's not like it'll be down to whether I did or didn't eat quite enough quinoa.
I suppose my advice would be, examine your reasons for wanting to postpone, and ask yourself whether they're truly going to change over the next couple of months if you do postpone. And remember, it's really normal to feel scared and overwhelmed in the runup to treatment.
Good luck, whatever you decide!