CFRA's Garrett Nelson says Tesla (TSLA) earnings were better than expected with its positive cash flow and signs that shifting revenue flow is helping margins. When it comes to timing, Garrett emphasizes to take roadmaps on new products like its Roadster with "a grain of salt." While he doesn't see the flying car generating significant revenue for years, he believes Tesla's full-self driving capabilities will. Garrett weighs the value a tentative merger with SpaceX (SPCX) will bring to both companies.