Rosemary (perennial herb (tender perennial in cold climates)) is classed tender perennial in the cited extension guidance. The timing rules below are relative to your local freeze dates — enter a location to turn them into calendar dates.
The rules this site applies
Method
Frost-relative window
Rule & reconciliation
Transplant outdoors
from the median last spring freeze to 2 weeks after
Oklahoma State Table 1: plant rosemary after the last spring frost (propagated by seed or cuttings; most gardeners set out purchased plants). Point rule given a 14-day span.
No start seeds indoors window: Seed-started rosemary is slow and erratic; the cited guide gives no indoor lead time, so no window is calculated.
Variety assumption: A slow-growing perennial; harvest lightly the first season. Not reliably winter-hardy in cold zones.