The timing of the events is irrelevant as far as the IRS and the tax code are concerned. The rollover to the 401(k) could have been done after the nondeductible traditional IRA contribution and the conversion to Roth and the reportable result and taxable result would be the same. You could even have done the Roth conversion followed by the traditional IRA contribution followed by the rollover to the 401(k) as long as all of the amounts remained unchanged (although it could get a bit off if gains and losses in the traditional IRA are different).
