It does seem based on the wording that we can expect raises for good performance effective Sept 1. But I wouldn't be surprised to see them not come for another year, just because IBM is always looking to save money at the cost of employee morale.
I received a bonus in mid-March for PBC 1 results. I didn't receive a raise in April like I usually do when I get a 1. I asked my boss about TCR at that time and he said he heard nothing about TCR for anyone. I asked around and people were saying their managers told them TCR was delayed a quarter. That would put it in July. However I asked around again, and people were saying TCR was effective in September, not July.
I received a raise effective July 1 out of nowhere, and I asked my boss if it was TCR for PBC results, and he said no, it was just an off-cycle raise to keep pay competitive. I asked him if it was MBA and he said he didn't think so.
I have no received a raise since. Typically I am not aware of a raise until I receive it in my paycheck, and then my boss notifies me of it after I already received it. So I may have gotten a raise effective Sept 1 but I won't know until my paycheck on the 15th.