Personally I disagree. I think that if you have 4 fish in your tank after 1.5 months you are stocking too fast.....let your biological filtration catch up.
I also think that you need to add more LR. You say that you have 10lbs. right now, and will be adding 25lbs. soon. Still not enough, IMO. Angels are voracious grazers, and require mature LR....
Speaking of tank maturity, your tank is only 1.5 months old. I would definitely wait to add anymore fish, but especially a Flame Angel. As I mentioned above, they are voracious grazers, and will need mature LR to graze from. Newly cured LR just wont do the trick, IMO. Plus, tank maturity brings water stability (hopefully).
Also, you mentioned that you are planning a reef eventually. Keep in mind that not all Angels are reef safe, and are hit or miss when it comes to reef compatibility. I'd say that if you add any Angel before you add corals you have a much higher chance of the Angel nipping at any corals introduced after the Angel. JMO