Back when I filed I expected to get a FICO score increase upon discharge but I didn't. Apparently it was the filing that moved things and in my case my scores increased upon filing. Suddenly my cards weren't 100% maxed out and I wasn't 100K in debt.
I disputed some cards that were not showing IIB before discharge the creditors updated them to show IIB. Most of my creditors updaged to IIB after filing but before discharge.
I would encourage you to dispute accounts that were IIB on a regular basis after discharge. I got rid of about half my IIB accounts, including AMEX, Barclay's, Amazon, Dell -- and others I no longer recall.
It is a waste of time to write a lender and ask for a goodwill deletion. They will never do it. They want you to suffer as long as possible. I can't say I really blame them.
The only credit I applied for before discharge was a shared secured loan with my credit union. Since I had zero open accounts at that point my score actually jumped a lot -- I think like 30 points. My scores upon filing were very low 500s.
Good luck on your rebuild. I see nothing wrong with getting a head start but don't go too crazy. You can get stuck with a bunch of low limit accounts and then the good lenders won't lend to you because you have too many inquiries and too many new ($500 limit) accounts.
FICO 08: EX-698, EQ-738, TU-721 - [8/2/2019] FICO 09: EX-748, EQ-785, TU-770 (8/2/2019) Mortgage: EX-737, EQ-769, TU-761 - [8/2/2019] NFCU NavChk 15K | NFCU Visa 50K | CapOne Venture Visa 50K | CapOne Savor 30K | Barclay Aviator MC 12.5K | Discover It 32K | Alliant 3% Cash Back Visa 25K | BECU CLOC 10K | BofA AK Air Visa 5K |Amazon Prime 10K. 239.5K Total Revolving. Alliant Car Loan 15K/31K BK 7 Filed 8/23/2013 - Discharged 11/27/2013.