Travel from Haneda to Narita

I am flying out of Kansai (Osaka) next Saturday arriving at Haneda at 16:15. Then I have to catch a flight at Narita at 19:25 for Sydney. Can you advise:

1. What is the best way to get to Haneda to Narita and how long is the travel?
2. Is this realistic - or do you recommend making different travel arrangement from Osaka to Narita?

Appreciate your help. Thanks.

You can go by train or bus: http://www.haneda-airport.jp/inter/en/access/traffic.html

Min. time seems to be 65 minutes by bus, about 90 min. by train.

If possible, yes, a direct KIX-NRT flight would be preferable, as it removes a possible source of delays. Most LCCs like Peach and Jetstar fly that route.

Transportation between HND and NRT is well-documented on this site.