Watch crystal for Pico?

Yes, that'll be fine.

If your iron has a relatively fine end on it then it should be fine.

For the best finish, I'd:

• use solder wick to get any existing solder blobs off the pads
  
• put fresh solder on one pad, and while it's molten push the crystal into the solder with a pair of tweezers
  
• heat up the other pad and add solder to make contact
  
  

It might be hard to get the soldering iron on to the pad, so i'd consider shifting the crystal over a little so you can be sure you have a bit more space to get the tip in

And first try it without the capacitors, because they can be a pain to do with a soldering iron as they're so small :)