If I take 4 mg of Suboxone around 2:00 pm this afternoon for how long will I be in withdrawal? Will it still show in my urine?

Should not be. Suboxone lasts approximately 12 hours ( half-life) but it is common that we often dose thru the day mimicking the previous cycle . Urine toxicology for workplace etc does not detect suboxone but it does detect heroin cannabis Cocaine etc.