First, you can either manually run the main class over and over again (possibly by a button or anonymous apex) or you can schedule the wrapper class.  You can schedule the wrapper class thru anonymous apex (click here for documentation).  You should be able to schedule this at any time you want - not just 1 am.   I recommend 10x per hour if you have that many available scheduled job slots in your system.  I recommend 10x as it will get you to 2400 of the 2500 daily limit from google.

Secondly, if you read thru the code you will see that the geocoder processes untouched records first for initialization and only when those are all processed will it look at the out of date entries where geocodeneedsupdate = true.

To be processed, records need at least a billingcity and billing state combo OR a zip code.

Here is some text code for the wrapper class:

static testmethod void TestScheduleGoogleGeoCodeUpdater() {
		Test.startTest();
		
       // Schedule the test job  
        String jobId = System.schedule('TestScheduleGoogleGeoCodeUpdater',
                ScheduleGoogleGeoCodeUpdater.CRON_EXP, 
                 new ScheduleGoogleGeoCodeUpdater());
                 
     // Get the information from the CronTrigger API object  
        CronTrigger ct = [SELECT id, CronExpression, TimesTriggered, 
           NextFireTime
           FROM CronTrigger WHERE id = :jobId];
  
     // Verify the expressions are the same  
        System.assertEquals(ScheduleGoogleGeoCodeUpdater.CRON_EXP, 
           ct.CronExpression);
  
     // Verify the job has not run  
        System.assertEquals(0, ct.TimesTriggered);
        
     Test.stopTest();   	
   } // test method      

Add it to the class and re-run your test coverage, you should get 100% on the wrapper class.   For technical reasons, it isn't possible to get 100% on the geocoding class.  You should get at least 85% though.

BTW, the geo code caching is useful when you want to render more points simultaneously than google's service will allow.  If you are wanting to render just one point on the map, you can do the geocoding in javascript.  As long as you don't send more than 1 request per 200ms you should be fine.

Hope this helps .....