I have a five gallon batch of apple wine that has been fermenting for about 5 weeks. The fermentation has almost slowed to a halt. Would tonight be too soon to try a bottle?
Way too soon by several months. It is time to rack and sulfite if you haven’t done that since pitching. At that point it’s a must to taste it and record your thought, etc.
* from a quality point pulling 750ml out of a five gallon carboy increases the risk of oxidation on the left overs.
* at five weeks back sweetening requires sorbate, will you keep it dry or sweeten? ,,, cider folks would pasteurize to stop the yeast,,
* the flavor will get less yeasty and carbonic over six months, do you like the flavor? all of us will rack around a month in and taste it.
as @Ohio Bob says, ,, no matter which way you go it is time for a dose of K meta to minimize long term oxidation risk.