Yowza. I think you're likely to get a lot of people telling you you should probably start with a lower dosage.
I've only taken ETH-LAD once, and at 100 mcg, so take my opinion with a grain of salt. However, the view I have heard from almost everyone I've ever spoken to who has used ETH-LAD has been that the intensity ramps up exponentially quickly with dosage increases and that 200-300 mcg is often a maximum dosage even for highly experienced psychedelic users. Based solely on the anecdotes I have heard from others, I would not necessarily expect to be able to walk and talk from 250 mcg for your first time, at least not in any way that doesn't require your entire focus or outside help. Some people will, but I would say it seems to be a real gamble. Speaking just from my one 100 mcg experience, ETH-LAD is clearly stronger than LSD in some significant ways, and that's not something I say lightly nor have said for nearly anything else ever. Tread with caution.
What I can say is that the body load, especially for an indole psychedelic, was definitely already very nasty for me at 100 mcg. The idea of jumping in at 250 mcg also terrifies my for this reason alone. I'm not sure whether or not there have actually been any reports of dangerous overheating or any other side effects becoming genuinely threatening from ETH-LAD on its own, but it is still an only fairly recently released drug which is apparently leaving the market due to not being popular enough, so it's entirely possible that enough people simply haven't taken it to find the danger yet. Tread with caution with that too, especially given the incredibly dramatic intensity increases with higher dosages. However, it's notable that, to my knowledge, a dangerous point has not yet been found, but the discomfort alone has been enough to keep me away from ETH-LAD since my first dose, though I do intend to return to it eventually.
Again, just my amateur thoughts.... Hopefully others with more experience will chime in as well.