Showing completion but not validation

I'm working on a wizard-esque form that will have multiple steps. I'd like to show that you've finished a step.

The catch is that we don't want to give the end-user the impression that the step is also valid yet, as the validation isn't happening until the last step. It may be valid, it may not be, but the step is completed for now.

I have this now:

default view:

(1) step 1...
(2) step 2...
(3) step 3...

As you complete a step, I wanted to change it to a visual state to indicate that you've completed that step. Right now I use checkmarks:

(✓) step 1 (completed)...
(2) step 2...
(3) step 3...

The concern is whether or not the checkmark is perhaps signalling 'valid' more than 'step completed'. Opinions? Maybe it doesn't matter? Any ideas on different/better icons/visuals?

If after Step 3 any step is invalid, we have the user start over. So it really doesn't matter from step-to-step which is invalid.