I like preworkout slin, but start LOW. Don't know what kind you're using, but I got hypo symptoms using 3iu humalog my first time. So just have plenty of carbs available to you in the window of action (depending on which slin you're using).
If I were to do it again, I'd start with post workout insulin until I got a good hold of how many carbs I needed per iu, as well as it's spike times. Start with 10g (a teaspoon is 4.3g) of sugar per iu of insulin you use. If you let everyone know what kind of slin you're using, people might be able to give you a better idea of when/how to take your carbs...