How to print a field in a view only when it appears first?
You can achieve this using the Grouping field setting in the view's Format settings. You will need to be using Fields (as opposed to Content) in the Format section of your view. 



In your Fields list, click on the taxonomy term field to open the field configuration. Check Exclude from display and apply:



In the Format section of your view, click on the Format Settings.



The Grouping field Nr. 1 select list is available in each Format type, so no worries if you have it set to HTML list or another format. Change the field from None to the taxonomy field you want to group by and apply. 



Your view will now show products grouped by the taxonomy term. From this point you can use the Sort criteria of the view to get the ordering of products or taxonomy terms you need.