I would definitely do the data collection whilst you have the opportunity to visit the country. I started my PhD in September 2010, and began data collection in February 2011 for various reasons (mainly as I had access to participants which I wouldn't have had at a later stage). However I was able to do this as I had done my Masters in a similar area, and therefore knew the specific topic of my PhD/gaps in previous literature etc.
You may have to put in a bit more work at this stage to ensure you're able to start data generation in May, but it's definitely possible.