Dental implants took 4 months (no graft needed) to osseointegrate and i will have to wait 2.5 extra months for the implant crown. is this unusual?

Unusual: My lab takes ten to forteen days to fabricate a custom post and crown. Unless the soft tissue is being recontoured, two plus months seems a bit long.

Implant timeframe: It depends upon whether they are upper or lower dental implants, the number of implants involved, the type of bone, the size, location and type of implants and most importantly the complexity of the case. Restoring two individual implants is quite different that a full reconstruction. We need more details. Most importantly you want quality and not speed. Discuss this with your own dentist.

Depends on...: The length of time between placement of the implant and the restoration of the implant depend primarily on the primary stability of the implant. This is best quantified by the insertion torque. If it is > 35 N-cm, then 4 months. If the insertion torque is < 35 N-cm, then closer to 6 months. If excessive lateral forces are exerted on the implant prematurely, then bone loss and failure could arise.