The stage where most knitwear orders are won or lost.
Counter sample against the catalogue body
Measure against your chart at every point, not only chest and length
Wash test the sample the way your customer will wash it
Re-measure after washing and record the shrinkage
Sign off a sealed sample that both sides keep
None of these five are published in the source catalogue. That is normal for a knitwear catalogue, and it is exactly why they belong in the first email rather than the last one.

100% Acrylic
Autumn/Winter · View style
65% Viscose, 35% Rayon
Autumn/Winter · View style
100% Acrylic
Spring/Summer · View style
80% Acrylic, 20% Metallic yarn
Autumn/Winter · View styleLead times are not published in the source catalogue. Ask for the sampling lead time and the yarn lead time separately, because the second one usually sits outside the factory.
For development: a tech pack, a measurement chart with every point defined, the intended fibre content and the care label you plan to print. For catalogue selection: the item numbers and the quantity.
Put it in writing on both sides. A sealed counter sample plus a written tolerance is what makes a later inspection meaningful.
Sample cost and sample lead time are not published. Ask for both in the same message as the quotation request.
Send what you have: a tech pack, a chart, a photo or just a list of item numbers. The first reply will tell you what is missing.