now there is something smart you two said, put holes in the cup. Lets not forget that the soil isn't going to dry for the next week and half or so and that root being soaked in water is going to harm it more.
Yes, i am suggesting to take the small seedling that has one root. I also said let it dry before doing so and since he is a new grower heis going to over water it again and again and leaving it be for the next two weeks isn't going to happen. I also, think he is smart enough to figure not to do anything crazy and follow a simple instruction while carefully perform the operation.
1- let it dry out - holes in the cup helps with this process
2- Once the soil is 20% moist you can CAREFULLY stick two finger's under the plant root ball al pick it up. Since the soil will be intact to the root it will not damage it and it won't give any transplant shock.
3- Hopefully you've already created your mix of 70% soil 30% perlite and than you can just put it in the new soil. Small amount of water and call it a day.