Can do, logged in can be easier for tracking stuff, but makes no real difference. I only got a dreamwidth account very recently, I'm still on livejournal, been there since about 2004. I just imported my blog over because I know a few people on here and it gives you the option to copy your entries to both blogs in one go. I figure with 12 years of entries I really don't want to lose, it doesn't hurt to have a backup.