I would never accept payment of salary that could change before I had the chance to exchange it.
Exchange it, why would you even mention about receiving your salary in bitcoin if you're just going to convert it back to fiat, make no sense.
Unless you get paid in the $100k plus bracket the price fluctuation in bitcoin has very little effect on how much you receive in your pay, the amount of bitcoin you will receive will be equivalent to the value of btc at the time of conversion.
Even a $50 change in the bitcoin price, which is big these days has would have only a small effect on the amount you would receive.
Let's say you get $500 usd in fiat each week, at $650 per coin you would receive
BTC0.76923, at $700 per coin you will receive
BTC0.714288 - a difference of
BTC0.054942 or about $35 usd.