We can collect 600 coins every 8 hours. Collecting times are explained at the bottom.

We get 5400 coins in total + 160 from the start= 5560 coins (coins from freebies not included)

For Wacky Dragon #550 we need 1100 coins. Wacky we need for the temporary Citadel quest.

For Farm Dragon we need 4750 coins. (two possible paths)

For Enchanted Dragon we need 10630 coins, so that is not for free.

If you buy out fields with fights instead of doing the fights you will need more coins.

Collecting times:

Open the eventwindow. In the lower left corner you see the timer (the picture is from another event).

This timer started with 2days,23hours,59minutes.

It will count down to 00d 00h 00m.

You have three timewindows of 8 hours every day to collect 600 eventpoints (coins).

Ignore the days , just check hours and minutes of the timer.

These are the timewindos to collect the coins:

23h59m-16h00m.

15h59m-08h00m.

07h-59m-00h00m

So you have 8 hours to collect the full amount of points. After that time a new timewindow will start and you start collection for the next 600 points. So it is possible to get ready with collecting 600 points ten minutes before the window ends and then after 10 minutes collect again 600 points because the next timewindow started. Just bring the time the timer shows in relation to the time your clock shows and you find the times for your timezone. I hope this is helpful.