That seems reasonable, though you may regret putting less ginger in. Reading back, it seems like you're asking when it will clear while the ginger beer is still fermenting. In fact, it even looks like you're fermenting this in the barrel you plan to dispense it from. This is probably just me misunderstanding, but if not, well...... You need to ferment in one vessel, then when fermentation is over, add priming sugar (so it'll prime and be fizzy), and then put it in the keg, and THEN wait for it to clear.