Well, in some of the manga and anime series the time that passes in the serie is not important, because its more important the story than the time (exceptions are normally School Life mangas and animes, like School Rumble). Taking reference of manga (never take it from Anime, its a wise advice) i think that at least it passed 1-2 years. But the time in Meitantei Conan is not important, so i wont try to think a lot the answer of this.
Btw, your post shouldn't be here, Pink Candy. somebody created another thread (probably) about the end of Conan, so dont start to write in another threads asking this question. Thats another wise advice.
My best friend its me, so i dont like to be my enemy