We have found that not all shetlands are ready to shear at the same time, and often the front is ready before the back
So here in the south of scotland some are ready in May, most in June, and a few not until late June, at least the bloomers bit. You will see when they are ready to shear by opening the fleece - you will see 'the rise' - a layer of what appears to be thinner fleece (the boundary between last years fleece and this years new growth), which is ideal to shear through. Once this layer is about 1/4 - 1/2 " above the skin you can hand shear. They will roo when the rise is slightly higher - a warm day is best as the lanolin is nice and soft then. If the britches are not ready, leave those bits for another couple of weeks (they look a bit ridiculous
). In first shear animals, the rise is sometimes less clearly defined.