Do a fim, not a toppping. u still have time, don't wait any longer or will be bad. This is the vegging time even on autos they have it too. keep the 20h a day for your auto at this rate and it will be fine. When start to flower just reduce to 18h.
Good luck. its a healthy plant. Top is not a good candidate now, in the early sprouts maybe, fim is better, allow space to recover and give u 2 to 4 more tops for each fim,