Hi my Bichon is 4 yrs 8 months is that too old to let her have her first puppies

I would say almost certainly yes. 

Assuming she isn't go9ng to be in season any day now that wioll mean she is likely to be close to five or over when they would be born.  

This would be considered the maximum age to ridk a forst litter in my own medium size breed, and toy breeds mature more quickly, and you have the added problem that relative to their adult size Toy breed puppies are quite large and by this age her pelvic bones will be less flexible giving a higer risk of complications at birth.

If she came from a respected reputable breder you could not do better and go back to them for another puppy.  You amy end up with a niece or great neiece and all the heartache and problems, not to mwntion expensse and responsibility for ahe litter is shoulderd by them.  Buying a puppy in will be cheaper too.