Assuming that it is the (to be) convict George Phelps who married Hannah Jackson, then:

• Bibe/Biby could still be his if the 1861 census birth year of 1845 is correct - depending on the rules of release or visits between spouses.
  
• Bibe/Biby could not be his if the baptism of 1849 was that of an infant.

The factual evidence around the convict George Phelps is:

• Born abt 1818 (from conviction records).
  
• 27 June 1843, convicted of stealing a ram lamb (Flaxley district) at Gloucester quarter sessions. Sentenced to 10 years. Gaoled in Cinderford gaol.
  
• 27 June 1844, embarked for van Dieman’s Land (during the probationary period of convict transportation).
  
• 15 November 1844, arrived in van Dieman’s Land. Worked in gangs for 15 months.
  
• 18 February 1846, emerged from gang.
  
• 1849 (Tasmanian convict muster), still present, but with his Ticket of leave (having served only 5 years of his 10 year sentence in Australia).

My supposition is that he then set sail from Hobart town on 5th November 1851 for Port Jackson (Sydney) aboard the Emma, as a passenger in steerage class.

The factual evidence around the Australian George Phelps:

• was born Forest of Dean abt 1819/20 (Death certificate and children's birth certificates).
  
• 1851/52 entered the colony of NSW.
  
• Married Mary Hawker (nee Vincent Nevell) 26 September 1853 at Sofala (New South Wales).
  
• Had three children (George, James, William).
  
• Died 3 March 1864 at Running Stream, from a horse fall.