By default the purchase and pick up times are defined when you make a new offer. If, however, you want to set specific buy or fetch times for a template, you can do so by clicking “Customize Order & pickup times for this template” to open the dialogue. Setting a custom order time window could make sense for example in the case of portions left over from breakfast or portions that need to be fetched warm right after its service at your venue ends.
Dietary settings are an important part. If you are uncertain about the fit of a meal to a certain diet, rather leave the offer untagged. However, if you don’t tag a meal, people with that diet setting might miss it: They will most likely not get notified for it and the offer will be listed faintly at the end of their offer listing. It is hence good to insert tags for diets to which the offer certainly suits. Note that some dietary options are included into one another automatically. For example, if you tag your dish vegan, it is automatically also tagged as milk free and vegetarian.