Bree day is sat can I just leave it on the plate till then?
Yes,,, it'll just get more yeast propagated, which is a good thing. Made my first ever starter a couple of weeks ago (sat on stirplate for about 48 hours), and wound up with 8-900ml of starter volume myself. (for a 5 gallon batch of approx 1.065 SG)
The fermentation was so aggressive, I had to use a blow off tube for the first time :rockin: Even then, the krausen crept all the way through a 1/2" diameter 5 foot long section of tube, into a pitcher of sanitized water.
For my second time using a stirplate/starter, I went with a 1ltr starter for my hefeweizen, which has a SG of about 1.050. Different yeast, different behavior. Good, quick fermentation with a thick layer of krausen and bubbles in the airlock.
Have fun and don't worry about the size of your starter... unless you're making a 20 gallon batch, which you already said is only 5 gallons.