Not sure if you have but you first should do a introduction of your self in the introduction thread. Simply tell us about your self and your practices/how long you have been practicing or if you just started talk about what got you interested.
But besides that! Unfortunately I am not familiar with this entity. But I know most are patient. If you feel the call to this being it could be for a good reason. 
I recommend looking through this site for info and experiences that others had with him and from there judge if you would still be interested in working with him. :3
To answer your next question, as some one new to this I wouldn’t recommend it yet. Yes blood is a common offering but a very potent one. Your blood contain basically a piece of your energy and by giving it to any being as an offering it can latter on make a energetic connection to that being. With a powerful offering comes responsibility as well. By also giving that offering you will also amp up the energy in the room and when applied to a sigil or other offerings it does send out more energy out so you will need to watch for unwanted lower “bugs” that might be drawn to the surge of energy. Normally they are not really a threat just annoying kinda like vultures picking at a lions kill. But as stated because you have yet to work with any demon, I would definitely wait especially until you get some of your senses up and going.