I'm not sure I understand the question. Can't say that I have experience with a 100% sativa, yet, but temps of low 70's and RH in the low to mid 50's will serve you well as an environment to dry your buds. I'll have the sativa experience in a few weeks and will take note of the drying time as suggested by
Bluey.
The hay smell goes away during the cure. Cure it and store it right and your weed will keep a very long time. Don't use any mechanical means to move the air in your drying space unless you need help controlling the temps, and even then just a very, very, gentle, gentle breeze. No lights either, dry in darkness, trichomes are fragile, light degrades the THC. Don't let the buds touch each other, that promotes mold.
In that environment the dry should take about 5 -7 days. After 3-4 days, snap a small stem. If it breaks clean you're good, if it doesn't, wait 24 hours and snap another stem, try several if you need to, it doesn't matter how long the buds have been drying, that stem test works as a guideline for when to put your dry weed into storage and begin the curing process. Once the weed is dry and put in storage, now you've moved to the curing phase, burp the container for a few minutes, at least daily, and if you need to more often, and watch the RH. If it creeps up open the container and let the weed air out for a little while. Cure for at least a month.
If your bud gets too dry, spritz some water on the underside of the jars lid, you are storing in glass jars, right?, that will raise the RH in the jar and help moisten your weed to the proper RH. During the cure and storage the RH should be around 60-62%.