Too much developer with toner

Ahhh! I don't know how I did something so silly, but when I mixed my wella t18 with developer I used 3.8oz instead of 2.8. I noticed something was wrong when it didn't start turning bright purple right away.   I have very blonde hair, and just did my roots yesterday and was planning on pulling out the yellow from the roots with the toner.

Will it make any difference at all to my roots since I mixed it wrong? I usually wash the toner out almost as soon as I am done applying, but now I don't know what to expect. It's been on my head for about 15 mins now, and is turning purple, but just not like it usually does due to my silly mistake!