Great job!
Yes, if you want to work on the Advanced Quant book now, a score of 48 is good enough.
Okay, so now you know what you need to do in future with regard to practice tests: they should always be taken under 100% official conditions. Don't do anything that wouldn't be allowed during the real test.
So that means: practice how much to eat and drink during the allowed breaks so that you don't have this same energy crash in future. (You don't want to plan to leave the room during a section - it will take longer than 1 minute. You have to raise your hand, wait to be escorted out by the proctor--who will have to lock the test screen--go through the security procedures to get out, go to your locker, eat, go back through the security procedures to get back in, be escorted back to your desk...and if someone else is there right before you, you have to wait for the other person to be checked in or out before you will be helped.)
Next, you need to think more carefully about how you manage your mental energy. It's good that you know what you do and don't want to do during IR and quant - but have you also considered verbal when making these decisions? Ask yourself: is this where I want to spend this mental energy? Or do I want to save it for verbal? Your mental energy is finite across the entire test; it's not like time, which renews at the start of each section.
What did you get on IR, by the way? If you got a 7 or 8, go for a 6 next time. Save that energy for later.
One idea that may or may not be feasible: the GMAT is testing a new program that would allow people to choose the order of the sections (within a limited set of options). Right now, it's not open to everyone, but if the tests go well, then I'm expecting that they will roll this out to everyone later this year. (I'm guessing - I can't predict the future, of course!) If that happens, then being able to do Q and V before you do essay and IR may make a significant difference for you. Something to keep an eye on.
Finally, feel free to take 2-3 weeks off. You shouldn't experience much atrophying of skills in that timeframe (maybe a little, but it'll come back once you get back into it). If you take more time off, you may see some loss - but then just react accordingly. Add some time and revision-type work to your study schedule.
If you do decide to take it again, you may want to consider ordering the Enhanced Score Report for your official test in order to see whether it gives you any valuable data about your weaknesses on that real test. More info on the ESR here:
https://www.manhattanprep.com/gmat/blog ... re-report/It doesn't provide a ton of data, and if the data is ultimately "you were about even across everything," then it's not hugely useful - but if it does tell you that there's a time or performance discrepancy in one area, that knowledge could be very valuable as you prep for your re-take. If you do get it, feel free to share the data here and we'll tell you what we think it means.
Finally, for verbal re-studying, add this to your analysis:
1) why was the wrong answer so tempting? why did it look like it might be right? (be as explicit as possible; also, now you know this is not a good reason to pick an answer)
2) why was it actually wrong? what specific words indicate that it is wrong and how did I overlook those clues the first time?
3) why did the right answer seem wrong? what made it so tempting to cross off the right answer? why were those things actually okay; what was my error in thinking that they were wrong? (also, now you know that this is not a good reason to eliminate an answer)
4) why was it actually right?
And start being crazy anal / systematic. You track the 5 answers in writing on every single problem. For RC detail questions, you check the passage for the proof EVERY time, even if you think you remember. You're trying to score in the 90th percentile on verbal; you can't afford many careless mistakes at that level. That anal-ness will also help to combat mental fatigue. If you're following your set process, every time, then you have built-in checks against the sloppiness that goes along with mental fatigue.