Is the light that you have currently working for you? Are you growing the corals that you currently have fine with your current lighting? If the answer is no, then get the light, but if the answer is yes, then yes, wait. You got like a paly and a zoa, they'll be fine in your current lighting. Now...
Do you have a back up plan if something goes wrong with your tank? Do you have quarantine? Do you have medicine in case you have to treat a fish for disease? Do you have extra salt? What's your water source? You've added a lot of livestock in the past few months, a faster pace than I even went and I have A LOT more experience in this hobby than you. IMO, spend the money that you have now on items that'll help you out with these things. It is said, an ounce of prevention is worth a pound of cure. Getting a fish or a coral is always fun, believe me, I LOVE getting pretty things to put in my tanks, but my
best purchases for my tanks? An RO/DI unit, extra power heads, an extra cheap tank or two, and a good tube of aquarium sealant. Look at me, I took these precautions and I
still got a macro bomb. I had extra power heads that I could've used if I had seen that the other had failed. My absence was the only thing that caused my macro bomb. If I had been present, I would've able to handle the emergency and I'd still have my 36g as a biotope.
I'm not trying to be harsh, I think it's great that you have this tank, and it's wonderful that you ask questions; you learn about how to care for these animals and I think this is extremely important.
L