i would like to ry to feed m son before th crying pnt. i know babis give subtle hintsbefore he crying starts, can you over feed a baby breastmilk?
I have not heard of anyone over feeding their child breastmilk. And, they are pretty good at spitting up if their bellies do get too full. 
One thing to watch would be, like momtomany said, to try to read the cues for other needs like burping, needing a diaper change, needing a nap, or just needling a cuddle. And when the baby gets a little older, it is good for them to learn to cope with adversities in other ways (not just nursing, which I admit is very comforting).
By the way, when my son was on a good schedule (not a newborn), I would know when he needed to eat and could feed him without him having to cry. 
No, you cannot physically overfeed a breastfed baby. That is one of the amazing things. Depending on how often they nurse, and for how long they nurse, the milk will be a different composition of fat calories, so that no matter how often the baby nurses, they will get the right amount of what they need (unless you’re not nursing them often enough at all, of course). The milk at the beginning of the feed is thinner, and the hindmilk at the end of the feed is richer. It is the optimum nutrition, so their healthy little bodies won’t be missing vitamins and nutrients giving them signals to eat more than they would normally (like what happens to teens and adults who are gaining too much weight because their undernourished bodies keep telling them to eat more). Also, when an infant drops off to sleep at the breast, they are barely sucking anymore and barely any or no milk is actually coming out then… they are just pacifying. Not so with the bottle… there is less variance in how fast the milk comes out. Your breastmilk adjusts in it’s composition in many ways to suit the needs of your baby, but the formula is always the same consistency that you put in the bottle… (sometimes, like in 3rd world countries, they can’t really afford formula and it is watered down for the baby). Even the antibodies that your milk provides will adjust in concentration, so that when your baby is weaning and drinking less and less milk, the concentration of antibodies will actually be more concentrated (to fight the same germs that you’re both exposed to). Breastfeeding is a really wonderful gift to give your baby, but of course the most important thing that your baby needs from you is your love and consistency.
On a more personal note, I am currently nursing our 6th baby. With my first baby, I did nurse her a lot… every time she seemed hungry or tired or upset… and we hardly ever heard her cry (you’re still going to hear her crying in the carseat or at diaper changes sometimes… ). She breastfed so often for so long, that I didn’t get my periods back for 2.5 years! With later babies, I did not have the time to sit with them to nurse all the time, so if they were tired or upset about something, I was much more likely to just hold them or carry them around and that worked too to help them stop crying. Looking back now, it is my personal belief that it is better not to breastfeed them for every emotional need of theirs. I wonder if it sets up a pattern for their life, that every time they are upset or bored they will run to the fridge (this is a little problem of our eldest now). I am no psychologist or anything, but I only mention my experience so you have something to think about when your baby is fussing and you are trying to decide whether or not she needs to breastfeed. They fuss for many things, and you want to meet the needs of your baby all the time to build that trusting relationship… sometimes they need a clean diaper, or need to make a BM, or they’re cold or hot, or tired and overstimulated… there’s lots of things that you can do to make sure your baby never has to cry very much.
Great advice, momtomany! Totally agree with you!
on demand!