This is again a choice for the individual to make for themselves. Personally I feel that the ritual bath before any spell work is very important. It helps to not just cleanse the body, but it also helps to put you in the right frame of mind to do the spell.
 

You will need some Sea Salt (if you can't find that Epsom Salts will do in a pinch) One or two candles. Not your spell candles!
 
 

Fill the tub and light the candles (incense is nice to if you want to use it) turn out the lights and relax. Focus on the flame of the candle, let your body relax all its muscles. When you feel calm and peaceful begin to think about the upcoming ritual you have planned. Go over it in your mind, focusing on what you would like the outcome to be.
 

Think of the Ritual Bath as the beginning of the spell you have planned. In other words, don't take the bath and go feed your cat! Make sure when you take your bath you know you are going to have the time and peace to finish you spell work.

The time you spend in the bath is again your choice to make. When you feel ready in body and mind, leave the bath and work your magick!