@insanehoshi Always something I haven’t thought of in this game that pops up. I hadn’t really considered hoarding IPP to utilize the lower unit cost that first turn after war starts!
I was going to suggest the same thing as @Noneshallpass too. You can leave a smallish screening force on the borders to prevent any deep penetrations right away. Enough to hopefully make blitzing unrealistic. It might cost you a decent amount of militia, but you can keep your more important units intact that way at least.