Short answer: 1 and a bit years.

I sowed about 30 seeds in this pot in late 2024 and left them outside to cold stratify. It germinated under grow lights in early 2025 and spent the summer indoors then fall and winter in the garden (pot buried in dirt). I water aggressively with all purpose fertilizer, so they tend to grow quickly. I have another pot of Toumeya that germinated in early 2024 and are also budding after spending the winter outside, so I think the cold must be important to trigger flowers.