Typically, I let MBV juices steep for anywhere between 1 and 2 weeks, although a few of them are good straight from the vapemail.
My "core four" flavors are Orange Dream Bar, Blackberry, East Coast
tobacco, and Amaretto. The ODB and blackberry can be vaped right from the mail, but for maximum flavor, I let them steep for about a week. East Coast Tobacco and Amaretto take about 2 weeks to steep for me.
IDK about Hawk Sauce and cucumber mint, but other ECF members may be able to answer your question better than I.