Here’s a really quick bit of code that will select the first row in an ext data grid after the store gets loaded. I use this all the time as I generally have events connected to a row click, such as populating a form, or showing a grid in another panel, and I have been told by many users that they do not like to fire up the app and see blank space, etc. This provides a quick solution.

Ext.getCmp('your-grid').store.on('load', function(){
                                var grid = Ext.getCmp('your-grid');
                                grid.getSelectionModel().selectRow(0);
                                grid.fireEvent('rowclick', grid, 0)
}, this, {
single: true
});