Simulink: Use of input as IC to S-function

Hi,

I have the following Simulink file. I want to use input E and F as initial conditions in mdlInitializeSizes for x0 in my 1-level S-function, however this seems not possible. As far as I've understood, the inputs are not loaded yet at this point. Is there any workaround I can use in order to utilize the inputs as ICs?

I read the following link which seems to be a similar problem, but I am having trouble understanding the suggested solution with a delay block. Any help is much appreciated.

https://se.mathworks.com/matlabcentral/answers/41050-weird-issue-from-a-simulink-model-a-simple-sfunction-block-in-series-to-a-switch-could-it-be-a

BR

Bastian