This is achievable if you create a condition and flip it to advanced mode. In the advanced mode, you can use the same expression syntax that Logic Apps uses. Expression reference is here: https://msdn.microsoft.com/en-us/library/azure/mt643789.aspx
From there, you may have to get a bit crafty. It looks like the dates that come back for sharepoint items are in this format: 2016-05-06T21:43:02Z
So, start by using the editor to do a basic comparison with the timestamp field, then switch to the advanced view. This will tell you how to reference the field you care about in the expression. I chose to use the 'Created' time when testing this.
Then, to do the actual comparison, we can trim just the date part from the timestamp, and compare it against a custom-formatted utcnow expression. So putting this into the advanced condition did the trick for me: @equals(substring(triggerBody()['Created'], 0, 10),utcnow('yyyy-MM-dd'))