Mushrooms don't need much light. If you can see the kit, there's already enough.
A few rules:
- No direct sunlight. It dries out the substrate and overheats the kit.
- Indirect daylight or a low-wattage lamp nearby works fine.
- Keep the kit away from windows where the sun hits directly.
Light helps the mushrooms know which direction to grow, but it's not what fuels their growth (that's the substrate).