I had the same problem just before winter last year with the 90 SSE ( 475, Klm.) This happened just after I changed the fuel pump, sending unit and filter. It cranks for about 20 seconds before it would start but always started right away after the second try. I never figured out what the problem was, but when it got colder it started on the first try so I left it. Now that it'* warmer out again it seems to start after about 3 to 4 seconds on the first try so I gave up trying to figure it out and live with it now. I hope you figure yours out.
Long Live My Bonneville 97 SSEi Dark Cherry