When do I change my ink cartridges

[TAZ0502]

I have an Instant Ink subscription and I recently received a shipment with all 4 ink cartridges.  I'm getting warnings about low ink supplies for 3 of the 4 but they're not empty yet.  When am I supposed to replace them?  When I get the shipment or when they become empty?  I'm so confused.  Your help would be appreciated and it's just about impossible to actually contact someone at HP to ask this question.  Thanks.

[Bob_Headrick · Accepted solution]

What printer model?  You mention four cartridges, which would indicate you have a printer with separate ink cartridges and printhead.  For these printers it is important to not let the printer run completely out of ink.  I would suggest replacing the cartridges as they are indicated as being low.

The Instant Ink program will generally initiate an ink shipment when you have two months of ink left at current usage.  In general you should replace the cartridges as they indicate they are low, or if print quality starts to degrade.

[TAZ0502]

Thank you Bob.  The printer is a HP OfficeJet Pro 8710.  

[Bob_Headrick]

The Officejet Pro 8710 will give a message when the cartridges are actually depleted, in addition to the low ink warning.  For this printer you could wait until the first color shows depleted, I would then replace all the colors if they were low.  Note that some ink is used whenever a new cartridge is installed, if they are all nearly depleted it is best to change them all at once rather than one by one.  Likely the color cartridges will run out pretty uniformly, when the first is depleted the others will not be far behind.  Color and black will generally need to be replaced seperately.