Jump Start Is A Wise Decision
You made a very wise decision to get some Jump Start for your non-feeding corn. Even if you have a male or female that is not feeding because of breeding behavior [thus explaining the non-feeding as non-pathological], there is no downside and lots of upside to using the JS to nourish your corn. Since JS is low bulk and low residue, it won't increase stress on your corn like a large food item would. Any stress from gently but firmly holding your corn and putting this in the mouth will be minimal compared to continuing to starve.
I bought a large tube at a snake show for $9.00.
Note that there is an applicator tube that comes with it. If you do use this, be sure to only squeeze out a small [1/4" or 6mm diameter, about the size of a green pea] amount into the anterior [front] of the mouth. Do not go too far deep into the mouth with this, to prevent choking. I prefer to use a blunt plastic tipped applicator [plastic Q-tip with the cotton removed] so as not to accidentally squeeze too much into the mouth. Which way you go is a matter of what's easiest for you to do safely.
Note that although one should always try to investigate causes of non-feeding, one shouldn't wait forever to try to get nutrition into a snake, unless there is a gut impaction that hasn't cleared [which may require a vet's help--you should suspect this if there wasn't a bowel movement after the last feeding, and there is a lump in the body from the non-passed food or stool--but you said nothing earlier about having observed this]. If the non-feeding otherwise turns out to be from parasitic or other infectious disease, this should be treated by a vet, but waiting forever to feed is not good.
When I was a beginner and had a non-feeding hatchling, I got way too much advice for way too long about trying this and that and being patient. None of it worked. Before I knew it, 2 months had passed, and I still hadn't found a vet yet--2 months of non-feeding for a hatchling can be fatal, and it very nearly was. I wish someone would have told me to either get to a vet 4 weeks earlier, and to get Jump Start and use it until I could get to a vet. When I did finally see a vet with my corn, it was just in time, and she's a healthy corn today because of that. But it was a close call.
Keep us posted on how this goes. If you use the JS every other day for about 10 days, and things go well, it might then be time to try a mouse [maybe a bit smaller than you normally give].
Best of health to your corn,
Doctor Mike