Mine is usually fully-thickened in 24 hours. I'll have to check my notes to see how much water I use.
I honestly don't smell the Optiphen at all, even in my unscented batches. But everyone's smeller is different, so maybe someone else who can smell it will be able to chime in here. If it doesn't go away in time, you could try a very tiny amount, like .5%, of a scent that you can tolerate. I typically use 1%, and can only smell it right when I put it on. Within minutes, I no longer smell anything. But since my smeller apparently isn't as strong as yours, I don't know if that will work for you.