That's the main reason why i made the number of drawn cards a variable. You have 7 or 8 cards in your starting hand and then can add as many additional cards, as you want. A 10 in the field D1 for example would mean your starting deck + 3 (or 2 if you didn't start the battle) cards from drawing. So usually turn 2 or 3.
Only "problem" whith this are sundials and hourglasses, as they are not included. But including them would make this calculation horibly complicated: Not only would one have to include the probability of drawing the dials / glasses, but the odds of drawing sufficient towers to supply them, too. In case of Quantum towers, one would need to add the chances of them to produce Time / Light Quantum. The players mark would interfere, too. Additionally one would have to distinguish between towers and pillars.
After finally solving all these problems, the player decides to bless his Oytugh instead of drawing an additional card with his sundial and the entire calculation is screwed up.
Therefore your best bet to get a reliable result is ignoring multi card drawing, and working with the number of cards drawn. In a deck that extremely relies on drawing several cards each turn, even in the early turns, you still could guess how many cards you draw per turn. Honestly, an educated guess would probably more exact than any calculation, as you could include the priority of your multidrawing cards.
(The other reason for making it editable, is the possibility of using it mid-game. In a tight game one might want to know whether you should use your quantum for that boneyard (i.e.) in your hand, or wait for a Bone Wall to be drawn.)