if you can keep the back of your hand under the light at the height your plants tops are and it doesnt get uncomfortable after a minute or so your good.
Its gonna make a huge difference, I veg until they mature and start showing preflowers/alternating nodes, works so much better than trying to flower them b4 they are mature and ready. if you want to keep vegging though you could, the fact its mature just means its ready to flower, not that it needs to be changed to flower right away.