Are you gathering the origin location for the directions on the same map page? If so and you would like the normal map to show until the address is entered you could have two maps on the page, one with the directions enabled that won't display unless the user enters the location, and the other would just be the normal map.
If you need to have just the single map but have it change to the directions map only after a user enters the directions you may need to add in a little custom code to get the map to display like this.
Do you have a link to the page with the map on it? I think having a reference for your current setup would be helpful.
