For more info on anti-emetic regimes, see here:
https://en.wikibooks.org/wiki/Suicide/Toxification/Antiemetic_regimen
I'm not sure whether to take 4x10g meto, or 6x10g, so I may just take 50g :-) Inevitably, there are no clinical trials to prove the ideal amount, so you'll just need to choose an amount you feel comfortable with.
Nitchke recommends a stat dose. Dignitas also uses this approach, and while N is different from SN, it makes me feel comfortable doing so also.
My only concern about using 30g SN (which is perhaps double what is likely to be a highly lethal dose for most people), is if there is an increased risk of vomiting at higher amounts. This is something we just don't know. Another individual judgment call.