op, accusing people of being trolls and being generally unpleasant will not do you any favours.
Tbh, there's a difference between having a view that someone is jumping into having a baby too soon and actively seeking to have other people agree with you on this point. And regardless of what your opinion is on this, it is your sister's life, and if she feels strongly enough that she wants a baby you're not going to prevent that from happening.
fwiw I think that if someone posted on here that they had been with someone for a year, had only been living together for six months and were planning to start ttc the general consensus would be that it was too soon.
But ultimately it is just opinion, and every situation and every relationship is different, and time doesn't actually mean anything in that context. The only reason I would say it was too soon would be because it gives a couple little time to be together as a couple before a baby comes into the equation, but how long someone has been in a relationship has no bearing on whether it will last or not.
People introduce their kids to a new partner after a few weeks for instance and many would say that was too soon, yet that couple may stay together for the rest of their lives. Equally there was a post on here recently from someone who had waited a year to introduce her kids, and her dp ended the relationship that night. You just don't know, and time is just that - time.
For me personally I had been with my h for seven years before ttc. We're divorced now.