Wow never thought of all these carby loaded stuff for labour, tis always interesting when others come up with such ideas.
Often I suggest going with instinct; your own body will tell you what it wants.
I woke up at about 2.30/3.00 with contractions (had been having some the previous evening but did manage to get a couple of hours sleep) initially sat reading but found I needed to sit more upright and rock thru the contractions, thinking I would disturb him unnecessarily decided to go downstairs at which point got an overwhelming desire for a glass of milk and a honey sandwich!. Now I never drink milk like that and rarely have honey sandwiches and certainly not at that time of the morning.
After this and a spell kneeling on the floor forwards over the seat of the settee, I then spent 2 hours in the bath, finally got to hospital at 09.00, used a bit of gas and air, and hey presto delivered at 11.20.
Clearly the 3.30 snack provided me with all that was needed. Yes of course we all know that sugar highs are followed by sugar lows none more so than a mars bar! I would think a sports alternative that has some sort of slower release form of good quality carbs would be better.
Basically if you fancy something in the early stages then go with what your body/instinct says you need. Do not try to eat a big meal; labour is hard exercise, and if you were doing a big race you would not eat a big beforehand as it would come back. Often sucking on boiled sweets helps in later stages.
Glad it continues to go well, baby head down and all that?