I’m not sure what @CMichGrower means by the tweak to be honest but @Covertgrower and him are right about it not being ideal for vegging plants.
HPS is far red and that will change the Morphology of the plants, not ideal but will still growif you want to learn how to maximize your 5 plants then look over at @Stonedrus he’s skirting rules of plant limits in an Intresting way.
If you haven’t unboxed the new light and can return it then I strongly suggest you return it and spend your money on an led fixture recommended by one of us.
Your 150 can veg your first grow while you wait on your led to to show up but for years going forward you will be thankful you went led and not HPS.
The best way to watch your plants to see if they are getting to much or two little light is the node spacing, if it’s to tight then raise lights if it’s to stretched lower lights… That being said HPS will grow short stocky plants because it’s far red lighting.so expect to have bush style plants.