Leaving seedling alone for 4 days?

My suggestion would be to transplant it into a larger pot. At week 3, you should be able to transplant no problem. When you water before you leave if you have transplanted it into a larger pot. Make sure you utilize proper watering techniques by saturating the entire medium. This is done by watering enough over about 10 min to have roughly 10-20% of the water come out the bottom of the pot. This sounds like a lot at the moment but I can assure you that if done correctly your roots will grow much faster and the plant will be healthier. Allow for the pot to dry back out before your next water, at this stage it is roughly every 4 days or so. I also like to pick the pot up just before I water to get a feel for weight, then once I’m done watering. After a few times and a few grows you can really tell when the plant needs water by just the weight alone. Also, if it is outside now, keep it outside. I hope this helps.