I can't wait to hear from you!
Aliás ficaria leve, perfeito, o modo sugerido por Atomina e complementado por Alentugano:
By the way, it would be smooth, perfect, the way suggested by Atomina and completed by Alentugano:
Mal posso esperar por notícias suas/tuas.
I can't wait to hear from you./ I can hardly wait to hear from you.