Distillers don't work to specific volumes - they go by taste. What you need to do is get a bunch of ~4oz jars, and then start distilling. With your starting volume, I would just collect about 1oz in each of the first two jars from the run, then a couple of jars with 2oz, and then go to 3 - 4 oz per jar. Dump the first jar collected. For the second jar, dilute it about 50/50 with water and taste. If it tastes terrible, dump it, otherwise save it for blending with the rest of the acceptable samples. For all subsequent jars, you need to dilute to about 40% ABV, and then taste. Save what doesn't taste bad, and throw out what does taste bad. When you have all the samples that taste ok, then recombine them, and proceed to oak aging, or whatever you plan to do with the product.
You will need a
"Proof - Tralle" hydrometer (a standard beer/wine/mead hydrometer
will not work) to determine the proof (ABV * 2) of each sample so that you can calculate how much to dilute it for tasting. You need a relatively large sample for proofing, but you should only dilute a small sample for tasting, and save most of the distillate for blending before diluting to final strength.
You should know that working with small volumes of feed material will make getting lots of cuts difficult, and each cut needs to have enough volume so that you can take a proof/ABV reading. The volume required will depend on the volume of your hydrometer sample jar.
You may also want to consider doing an initial stripping run, where you collect everything that comes off, until the still output ABV drops below your initial feed stock ABV. Then do a second spirit run where you collect the many cuts that you will use for tasting and selection.
Brew on