2 mins per lane.
Don't sweat it though. Many winter leagues don't time.
And it's more than you likely need.
And many fear it before, are a jumble when first on it, and I don't know anyone that can't cope after doing it.
My hands were shaking so badly on my first timed lane it was visible to me partner and I could barely load a pellet. 5 years and 5 months later I won the national and two regional showdowns, all in the same year, all timed at 1 min per target. You'll be fine.
Brian's advice is good. On positionals I do them kneeling for ranging and range target 2 first. Then all I have to do is remember the range of target 2 during target 1. It's just a number between 8 & 45. It's a good enough technique that it still works for showdown speed.
BFTA/NSRA County Coach
CSFTA Chairman/BFTA Rep