If you bump the sg, I'd recommend a mix of 2/3 organic cane (light turbinado) and 1/3 corn sugar. That is closer to the apple sugar taste. But first double check the sg if you still have some juice left over. 1.040 seems low. If you decide to do it, you can add it tomorrow - or in the next few days for that matter. Add it a little bit at a time though, so it doesnt shock the yeast.