Harvesting tea

I am looking for the best time of the year to harvest leaves for tea ... or is there a best time?

When I was looking at growing tea in Scotland I'm sure I read that the first harvest of the year (as early as mid Feb.) Is the best quality.  I found tea harvest which seems to bear this out.
I've still got a plant, but it's getting smaller year on year.  I'm thinking of moving it either into the polytunnel or to my new blueberry patch....

i imagine different herbs, the rules may be different. if you’re talking true camellia sinensis tea, it’s like nancy says, the first harvest in the spring, as soon as there’s enough new growth to pick (here that’s usually in may).

For herbal teas, I was told it's best to get them earlier in the season, before the plant bears fruit or goes to seed - but better late than never. I'm thinking of things like raspberry leaf, as an example.