First grow on a low budget

First-time grower here. I'm attempting to grow with minimal materials, without using a a grow box, inside my bathroom. The bathroom lacks a window, ensuring it remains 100% dark without lights, and it has a fan/ventilation system running 24/7. I've improvised a makeshift tent using a cardboard box. Eventually, I plan to remove the pot from the tent, leaving it in the bathroom by itself. My strategy involves maintaining a 12/12 light cycle as soon as the plant enters the vegetation mode. The goal is to have a small plant and harvest it as quickly as possible. I understand this may not be the most efficient use of resources, but I need to complete the harvest before the end of March, and a larger plant is not feasible. My soil is BioBizz - Dutch Origins - All Mix - World Wide Organics Fertiliser: Biotabs Organic Slow-Release (2 tablets) Day 1 - 09/01 - Germination on paper Day 3 - 11/01 - Transplanted seed to pot Started Light cycle 18/24 Watering 50 - 100ml per day Day 5 - 13/01 - Sprout Day 9 - 17/11 - Plant is 10 cm tall, but very thin Day 10 - 18/11 - I relocated the light from a 60cm distance to a 40cm distance from the plant. Despite no increase in height, the plant began developing a new set of leaves. I suspect that the previous lighting arrangement may not have been best for the plant's growth.