Hello everyone,

I have a very basic question. I searched the web and I couldn't find enough information.

Please refer to these attachments:

When reading the score, when do the players start playing the glissando/portamento effect? Right from the beginning of the note that has glissando/portamento sign? Or is it at the end of that note when moving to the other note?

My guess is that it starts right on the note that has the glissando/portamento sign. If this is the case, is what I'm doing in the attachment the correct way of annotating it? The first picture is the slow effect, where the bottom one has faster portamento.

another small question: do I need to have a slur between the two notes that have glissando/portamento? Can I have it as in this image:

Thank you all in advance. I will really appreciate it if examples from famous composers and scores were included in the answer.