The fact HCQ has immunosuppressive properties that have been used for diseases like lupus should definitely give pause when talking about its use for an infectious disease where you want your immune system to function properly. Generally speaking the earlier you get a drug the better, and prophylaxis is about as early as you can get a drug, but in this case mechanistically you probably want a robust immune response out of the gate to keep the virus in check early, but then as it progresses into the lower repiratory tree there may be some negative effects related to the immune system run amok (like some variant of cytokine release syn), a drug that as part of its MOA can dampen immunity to some degree makes sense. However if you believe HCQ has direct antiviral effects then taking it earlier and even prophylaxis may outweigh the potential risk early on
So IMO, prior to having data from RCT to properly guide therapy, I would opt to not take it for prophylaxis but would want it on board early once viral infection is confirmed (and I am on record thinking the drug is at best a 50 50 proposition wrt efficacy although the small randomized trial may have swayed me to be a tad more optimistic now)
If given the option I would still take remdesivir if I got covid over any other drug out there now - until perhaps the covid targeted Mabs reach the clinic
JMO