backdoor roth contribution with 401k rollover?

From what I've read, doing a backdoor roth conversion has to be done on a prorata basis for everything in every IRA I own. Currently I have a 401k with an old employer that I want to roll over into an IRA. I also currently have $0 in traditional IRAs. If today I make an IRA contribution from non-401k funds and then roll it over to a roth for the 2015 tax year, will any 401k rollovers to IRAs that I do later on in the current calendar year affect the roth backdoor prorata amount?