And for my money, the best show in TV's greatest decade was Lost in Space. It's impossible to describe what watching this show was like in the 1960s. It's an experience that simply can't be re-produced today.
The reaction reaches its peak about 48 to 72 hours after the PPD is injected. Waiting too long or not long enough may cause an underestimation of the reaction and, therefore, affect how the test is read.A positive test will cause redness, itching and a raised, hardened area of skin called an induration.
There is no time period you must wait between tests, although it would be a good idea to take a little time to study the drivers manual again. I assume you would just have to show your receipt, but I don't know that for sure and the web page doesn't say. Source(s): http://www.dmv.ca.gov/dl/dl_info.htm#two...