Not quite. The idiom is "to get off on the right foot," though "wrong" is probably more common. Since this idiom means "to start successfully" the verb start is not necessary. The second part is also not quite right. The idiom is "to have chemistry" with someone, but it really is usually used to describe a connection that doesn't require effort. So, if you have to "try to find" a connection, it isn't really chemistry. Those two idioms seem a bit redundant when used together, so it might be better to split them up, especially since it is a bit weird to use the last clause with the first idiom. "To get off on the right foot" already means something is successful, so it isn't necessary to also say it is promising. Here is my suggestion: "They really got off on the right foot. They had chemistry with each other, which was promising."

Hi Simba, I see what you're trying to say. Here is a better option: apparently they got off on the right foot, trying to find chemistry between themselves. To get off on the right foot means to make a good/promising start at a situation. We can also get off on the wrong foot, which, obviously, means the opposite: to start a situation in a bad way.

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