you don't have to get kills when you dive as Winston. keep that in mind. a lot of the time you just dive to cause a disruption or to create space for your team. only commit to a dive with the intent to kill if a team fight has been initiated or you have spotted someone out of position. as far as bubble timing it depends on who you're diving. if you're diving a zen, ana, or McCree bubble early to block zen's volley, ana's sleep, and McCree's flashbang. make sure to dance inside and out of your bubble. as far as positioning that depends on the enemies team comp. if they have a genji or tracer or divey heroes you might wanna stick with your backline more but if they don't then position yourself on high ground so you can drop down on targets and don't have to waste leap to engage. look up 1 Winston tip for every hero by KarQ on youtube as well, its a big help