Besides the shipping option mainly depending the delivery time, the following points are also influencing factors.
Your destination: the shipping time to some country is different from the other countries because of your location.
The package weight: the package over 21kg will arrive you one day later than that of small package under 21kg.
Our courier processing time: our available couriers are optional, and their processing time is one different from that of the other ones. And for several countries, only part of our shipment is available, For example, items to Russia, only EMS is available. And Singapore Post to USA, it only costs 8 working days not 12-15 working days.
Our items stock status: as usual, we will ship out your package in two days after receiving your payment, but for a short time our product is out of stock. When we meet such condition, we will try our best to send the package to you as soon as possible.
The harsh weather condition and festival holiday: sometimes the package shipping time will be influenced by the harsh weather condition and festival holiday.