I'll bet ok. a month before. So far I'm very happy with it. Went through several car washes with no problems. Also, we've had a couple of rainstorms and so far so good. Here is my advice just in case. Take your time and read the instructions carefully. Once it is in the desired position, use both hands to smooth it side to side. After that, here's what I did: I got a small jar (the size of a tomato sauce). I started at one end and rolled the jar all over the lid, pressing down on the jar with my palm. I did this 4 times in one direction to make sure all the air came out. It worked well. Much luck