It's great to start off your programming with PHP since there are big industries build around it.
Wordpress and Magento is PHP based and there are a lot of demand around these platform. Almost every businesses in the US/UK want a website or want to redesign their websites. It's easier for designer/developer to make money from PHP.
If you are looking to start learning PHP, follow these:
- Pick a framework
Wordpress, Magento, CakePHP, or Code Igniter. Pick one and master it. It's easier to start from these platform because there are many documentation and tutorial around them, it will be a lot easier to start out with these.
- Try creating your personal site with your chosen platform
If you chose Wordpress, try creating a site (maybe your personal site) using Wordpress. I've learned that it's will be easier and faster to learn if you assign an assignment to yourself.
- Follow these Assignments
Nettut+ has written a very nice list of assignments for you to follow. Check it out: http://net.tutsplus.com/tutorials/php/the-best-way-to-learn-php/
The time it took to complete this goal is: almost 7 years