I think the best time to buy a bitcoin is now if you have not bought yet.  Because bitcoin value fluctuates at lot. Bitcoin offers a number of benefits and advantages.  I think you should buy a bitcoin now before its price get more higher.  Now talking about when to sell the bitcoins is I will say best time to sell bitcoin is not time.  After buying bitcoin you should keep it with you for a long period of time.  Its value will increase and benefits you .  I will suggest to buy a fixed amount even month and to keep that money with yourself  until it get higher.