I'm in the same boat. Watch how he does tonight. Swinging a good bat, or rusty? Agressive on the basepaths, or tentative? That will give you a good idea whether to subsitute him for another of your players tomorrow, and the rest of the week.
By the way, I decided to drop Shannon Stewart tonight, so Giles is available for me tomorrow. (Stewart was leading my team in TB, but not hard to cut when I have Guerrero, Berkman, and Giles, with utility man of Derrek Lee or Dave Roberts.)