That's plenty hot enough if your iron is accurate.
Cleanliness is everything, if the board is tarnished or covered in fingerprints
clean it first. Copper is much harder to solder to than tinned copper, using wire
wool to get it clean and free of oxide is usually the first step with bare copper.
Make sure no fragments of wire-wool remain on the board though.
The most reliable way to wet a joint is to place the end of the solder between
the iron and the joint, so as the iron melts it the rosin flows all over the joint
and prevents oxide formation. Rosins job is to destroy oxide (its a reducing
agent).
When handling lead based solders always scrub your hands thoroughly clean
after working. Consider safer alternatives.